Watch Nellie the sea otter stack plastic cups (VIDEO)

Eric Pfeiffer
The Sideshow

The Point Defiance Zoo & Aquarium in Tacoma, Wash., is widely known for its diverse collection of marine life. When I was growing up in the Pacific Northwest, it was one of my favorite destinations to see massive sharks and other amazing creatures on display.

This week, the zoo released a video that is quickly going viral, showing Nellie the sea otter displaying some fascinating behavior as she stacks a series of plastic cups while floating on her back.

It's all the more impressive as Nellie is not merely stacking the cups in a reflexive motion but consciously arranges the cups in a stack from largest to smallest. And yes, it's also quite adorable.