Spasmosaur

The Spasmosaur was a creature which appeared in the fourth season of the 2012 animated series Teenage Mutant Ninja Turtles.

Description
A giant monstrosity several time the height of a man, the Spasmosaur was a creature which was kept captive by the Triceratons in order to fight in their battle arena. It had mottled blue skin, a blob-shaped body with three gaping mouths stretching across nearly the whole width of its “torso,” a multitude of large green eyes, and six long squid-like tentacles covered in suckers. The monsters only weak point was a small white spot located on its flank.

History
After the Turtles were captured by the alien Triceratons, their Emperor decided that they would be sent to battle in the Triceraton Arena. Their first opponent was the fearsome Spasmosaur, but luckily for them a friendly prisoner named Zeno filled them in on the Spasmosaur’s single vulnerability. Donatello was able to pierce the weak point with his staff, releasing a sticky purple ichor and causing the injured creature to flee in pain.