Who lives in a pineapple under the sea? SpongeBob Square Pants! Absorbent and yellow and porous is he! SpongeBob Square Pants! Get the perfect fish tank accessory for kids and big kids alike with this SpongeBob Squarepants home ornament. atch your fish swim in and out of the safe poly-resin and hollow designed ornament and create your very own miniature version of the underwater ‘Bikini Bottom’ world of SpongeBob Squarepants. A great way to teach your children about the fun and responsibilities of keeping pets.