This number--called a mole--is a basic measuring unit in chemistry ... The word "mole" suggests a small, furry burrowing animal to many. But in this TED-Ed lesson, we look at the concept of the mole ...

There are some animals that only come out at night and they are called nocturnal animals ... straw for their burrows and play in the dark. Moles live in holes, so they like it dark as well.

As in some insect species, the queen is the only naked mole rat female to breed and bear young. Worker animals dig the burrows that the whole clan inhabits, using their prominent teeth and snouts.

Hidden beneath the dunes, a mysterious creature glides through the sand. This is not one of the giant worms of Arrakis in Frank Herbert's sci-fi epic, Dune. Rather, it's an enigmatic and tiny mammal ...