Happy Aquarium's own SpongeBob SquarePants
For non-fans such as myself, it would've been nice it they added some functionality to the character. I mean, he looks like a giant scouring pad, which means he looks like the perfect thing to wipe off algae from a tank. But alas, he's just there to look spongey and rock those shades.
Either way, Happy Aquarium expects him to be popular, so he'll only be around until April 29th, 2:00 p.m. PST.