How can a sponge live underwater? SpongeBob SquarePants

SpongeBob is a sponge that lives in Bikini Bottom, which is a town under the sea. He lives in a pineapple and has a pet snail named Gary. His best friend is a starfish named Patrick Star, and he is also good friends with an astronaut-suit wearing squirrel named Sandy Cheeks. SpongeBob is an employee at the profitable Krusty Krab where he is known for making the BEST krabby patties in all of Bikini Bottom. He is at best indescribable. His laugh is unforgettable. I've never seen a sponge like him before.

As you can see, on land SpongeBob and his friend Patrick are regular objects -- a household sponge, and a natural starfish.

BUT, as you can see, when placed underwater, they become alive which is why I suspect they both have a fanatical group of followers in mostly children and even some adults.

Very peculiar...

...Does SpongeBob have special powers that Nickelodean doesn't want us to know?

...Is SpongeBob a defected sponge, and that is why he sinks?

...Is SpongeBob NOT real?

Judging from his appearance, it appears that SpongeBob is of large pore hydro honeycomb foam descent. Sponges of SpongeBob's kind are typically found in our kitchen sinks, and according to Sydney-Health.co.uk, they have a density ranging from 28-32 kg/m³. The density of the ocean is about 1,207 kg/m³. As we've learned in science class in 6th grade, any substance or matter that is less dense than the body of liquid it is submerged in will not sink. For example, oil is less dense than water which is why it floats on top of water. A sponge of SpongeBob's kind is significantly less dense than the ocean, and thus SpongeBob defies science by sinking into the sea instead of floating on the surface of the sea. But how can this be? Is science wrong? Is SpongeBob really an anomaly?

SpongeBob SquarePants IS A SPONGE! He just has a core made out of heavy metal!!!! That's why he sinks and can live under the sea!!

See! He's a ROCK STAR!!

Heavy metal!