Here, Sponge, here

"The common sponge, the thing we wash dirty plates and cars and toilets with is a plant."

The sponge is an animal, though not the kind that will fetch. Yes, according to the International Council for The Exploration of the Sea, "Sponges are some of the oldest multicellular animals and have been in our seas for more than 600 million years." Hey, who knew? I always thought it was a plant too.