Is it ensure, insure, or assure?
Plural megatheriums or megatheria
A large, extinct ground sloth of the genus Megatherium that lived from the Miocene through the Pleistocene Epochs, primarily in South America. It was as large as an elephant, had long curved claws and teeth only in the sides of its jaws, and ate plants. The megatherium was more closely related to the modern two-toed sloth than to the three-toed sloth.