The Cosmos Stones are powerful items that were sought by the Spectral Space Pirates in Dinosaur King: Mesozoic Meltdown (season 2), and the D-Team spends the season trying to stop them from collecting the Stones.
The Pterosaur states that the Cosmos Stones balance the power of the universe, and of all time and space. According to Seth, the seven Cosmos Stones were created alongside the Element Stones in an enormous explosion a long time ago, and came to Earth in the meteor that hit 65 million years ago and wiped out the dinosaurs. They are small, spherical glowing jewels that are colored to correspond with the Dinosaur Attributes of the Stone Tablets; they are translucent, with colored sparkles sometimes visible floating inside. On their own, each is dangerous. Although their specific effect is left mysterious, no person can touch one with their bare hands without being injured somehow (Spartacus is the only person who can touch the Yellow Stone, being somehow immune to its harmful effect), though using as little as a cloth can allow someone to safely hold one, and they don't seem to affect androids. When all 7 are combined, they will (according to Dr. Ancient) release enough energy to destroy the Universe ten times over! When they merge in Clash for the Cosmos Stones, they form the Dark Pterosaur.
The Cosmos Stones are scattered across the world and throughout history. Given how the Black Cosmos Stone is found, however, it's unclear why jumping through time is needed to find all of the Stones, as they should all be present during the same time period (perhaps the Space Pirates are simply seeking them at the easiest times to be found, such as when others are already looking for them). Finding the Cosmos Stones is the Spectral Space Pirates' ultimate goal, as they believe they will allow them to control the universe. They time-nap the D-Team's parents to make Drs. Ancient and Cretacia build a reliable Cosmos Stone locator, which the scientists build and purposefully sabotage.
Seth believes that merging the Cosmos Stones will cause the destruction of, not only this universe and all of timespace, but entire dimensions, and then restart the universe. He wished to be in control of this new, restarted universe, but later decided that no one should control this much power, and, with the help of the Pterosaur, destroyed the Cosmos Stones and the Dark Pterosaur.
All but the Black Cosmos Stone correspond to Dinosaur Elements. They can draw in dinosaurs of their own Element, and power up or weaken dinosaurs depending on what Elements the Stone and dinosaur belong to. When Terry and Paris swallowed their elements' Cosmos Stones, they went out of control, but Genie didn't (probably because Genie (Water) ate the Red Cosmos Stone (Fire), so he wasn't influenced by it as much).
Seth then pretends to defect from the Space Pirates in a ploy where he steals the Red and Green Stones, after which the D-Team and Alpha Gang get the Black Cosmos Stone. When they try trading a fake Black Stone for their parents' return, Seth steals the 6 Stones the Space Pirates have and commandeers the Backlander to acquire the real Black Stone, but the Stones are knocked loose when the Space Pirates ram them, Rod and Laura gathering 6 while Seth escapes with the Black Stone.
A planted Gel Jark later downs the Backlander and retrieves the other 6 Stones for Seth, but the Space Pirates attack and levitate up all 7, merging them into the Dark Pterosaur. After the Backlander breaks through its outer shell with the help of a Fusion Move, Seth steals and pilots it, shielded by the good Pterosaur, to ram the Dark Pterosaur's true inner body, and the Element and Cosmos Stones cancel each other out, presumably destroying both sets.
The Seven Stones
Yellow Cosmos Stone
The Yellow Cosmos Stone was in the possession of Sophia and Spartacus's family in Ancient Rome. Spartacus was one of the few people who could touch the Cosmos Stone safely, and in fact it gave him immense strength and power, letting him conjure a large electrical energy blade from his sword, stemming from the Stone's connection to the Lightning element. When Spartacus was captured by the Roman Army, Sophia took the Stone to Spartacus with the D-Team's help (Chomp seemed unusually drawn to it, as it corresponded with his attribute, Lightning). Spartacus used it to fight Spiny and Shear's Yangchuanosaurus in the Roman Colosseum, but lost it to Shear when he tried to escape with the other slaves. It was the only Cosmos Stone to actually be called a "Cosmos Stone" by those from the time period who knew about it.
The Yellow Cosmos Stone attracts and strengthens Lightning Dinosaurs.
Blue Cosmos Stone
The Blue Cosmos Stone was hidden in a small treasure chest on an island in the Caribbean Sea rigged with the ability to flood and partially sink to match its treasure map, possibly as a result of the Stone's connection to the Water element. Jim and his father went looking for it, believing it was able to cure the sickness that had been spreading throughout their village. Jim was the first to actually find it, but Shear stole it seconds later when her boomerang snagged the entire chest. Despite featuring in the arc, Spiny was never close enough to be drawn in by it, making it the only Cosmos Stone to never affect the main dinosaur of its Element.
The Blue Cosmos Stone attracts and strengthens Water Dinosaurs.
Purple Cosmos Stone
The Purple Cosmos Stone was hidden in a chamber in the heart of a mountain in Ancient China with a huge boulder blocking the entrance, its connection to the Earth element letting it "seal" the mountain off from would-be intruders. After struggling with the D-Team, the Space Pirates were eventually able to make a monk, Sanzo Hoshi, seemingly chant open the stone door. The rock had actually been shifted by Tank's stampeding, after she had tunneled up to the top of the mountain, drawn to the Stone (as it corresponded with her attribute, Earth), and had stared at it, throwing her into a temporary uncontrollable fit. Although Zoe reached the Stone first, Foolscap snatched it with a chain whip.
The Purple Cosmos Stone attracts and strengthens Earth Dinosaurs.
White Cosmos Stone
The White Cosmos Stone (in actuality being a light blue), was hidden in a cave behind a waterfall in Ancient Japan. Under the name of the "Half-Moon Stone", it was sought by Shogun Tokugawa and Hanzo. After being separated from his bodyguard, Tokugawa helped the D-Team find the cave it was hidden in. While the rest of the D-Team and Alpha Gang were helping to save Zoe, Tokugawa, and a bear cub after a cave-in, Ace led Rex to the Stone (as it corresponded with his attribute, Wind), but it was taken by Hanzo in the confusion after Gabbro tried to take it. It was later taken by Takeda's squad of female ninjas, but he suffered whatever negative effect the Stone gives when he picked it up with his bare hand, and Shear took it in a cloth.
The White Cosmos Stone attracts and strengthens Wind Dinosaurs.
Red Cosmos Stone
The Red Cosmos Stone was hidden in the treasure cave of the 40 Thieves in Ancient Persia (Iran). It was swallowed by Genie and increased his strength (although the Stone corresponds to Fire, Genie's Water attribute beats Fire, so he wouldn't be impacted negatively like a Wind Dinosaur would be, which loses to Fire). Throughout the entire story arc, no one knew that Genie had the Cosmos Stone they were all looking for until he was beaten by Chomp and Ace after being controlled by Shear. The Stone was then picked up by Helga (being a robot, she wasn't affected by it), making it the first one that the D-Team/Alpha Gang were able to successfully retrieve. Chibi Terry briefly grabbed it in his mouth and became hyperactive. Later, however, Seth stole it when he tricked the D-Team/Alpha Gang into thinking he was good again.
The Red Cosmos Stone attracts and strengthens Fire Dinosaurs.
Green Cosmos Stone
The Green Cosmos Stone was hidden in the eye of a statue in the glowing moss-overgrown basement of Vasasi Castle in Renaissance era Paris, France, the plants likely growing due to the Stone's connection to the Grass element. Calling it the "Blue Eye of Gaia" (despite it actually being green), the Royal Mother (standing in for her child son, Louis, the true King) sent Cardinal Richelieu and French soldiers to find it. The Space Pirates quickly made themselves an official part of the search team. While battling Maximus, Zoe found the Stone in the eye of a statue and had Paris swallow it, which gave her enough energy to overpower Maximus; its power drove Paris out of control, but Zoe recalled her, the Stone falling to the ground. Richelieu almost reclaimed it, but Louis finally stepped up to his birthright position of King and gave it to the D-Team. In the next episode, however, it was stolen by Seth when he tricked the D-Team/Alpha Gang into thinking he was good again.
The Green Cosmos Stone attracts and strengthens Grass Dinosaurs.
Black Cosmos Stone
The Black Cosmos Stone was hidden in a volcano in Stone Age Japan. After Brontikens caused it to erupt, the Stone flew through the air and was eaten by a mammoth. After escaping, Max realized that he and his father had found a mammoth skeleton buried under volcanic rock on a dig three years before the present, and Jonathan took them to that same day and time, where Dr. Z retrieved the Stone from the skeleton. When Seth tried without success to claim all 7 Stones, this was the only one he escaped to the present day with.
Though nothing was demonstrated onscreen, the Black Cosmos Stone could possibly attract either Secret Dinosaurs (unlikely, as this element didn't exist until Dr. Z's Pachycephalosaurus), any dinosaur that finds it, or it might not directly attract any Element of dinosaur. It appears to be a rough parallel to the Center Stone of the Element Stones in its seeming detachment from the Element distribution of the other six members of its group, neither of which have their exact roles spelled out.
- There is no Cosmos Stone nor Element Stone for the Secret Dinosaurs, owing to Dr. Z inventing that element by experimenting on dinosaurs after the fact.
- The Green Cosmos Stone being called the "Blue Eye of Gaia" in the English dub, Zoe later describing it as "really more of a greenish blue", likely indicates the original Japanese name used the word "ao", which today means blue, but historically could mean blue or green.
- The Cosmos Stones share numerous similarities with the Infinity Stones from the Marvel Cinematic Universe, and their original Infinity Gem comic counterparts.
- They are small, often glowing objects of different colors.
- They are objects of immense power that cannot be safely touched with bare hands.
- Whoever possesses/unites them can potentially control/destroy everything.
- Besides the bare hand holding part, they also share many similarities with the Chaos Emeralds from the Sonic the Hedgehog franchise.