Underground dinosaur cave

An underground dinosaur cave is located at the core of the Earth in the 1987-1996 series. The turtles discover it in the season 3 episode Turtles at the Earth's Core when a dinosaur has broken through the crust and into New York City. In the cave live various prehistoric animals.

Sunlight can't reach into the cave. Instead, life there relies on a crystal atop a tall mountain. Krang and Shredder want it to repower the Technodrome, and the turtles must stop them.