Porcelain crabs are decapod crustaceans in the widespread family Porcellanidae, which superficially resemble true crabs. They have flattened bodies as an adaptation for living in rock crevices. They are delicate, readily losing limbs when attacked, and use their large claws for maintaining territories. They first appeared in the Tithonian age of the Late Jurassic epoch, 145-152 million years ago.

Porcellanidae. Retrieved May, 08 2021, from en.wikipedia.org/wiki/Porcelain_crab.

Petrolisthes eriomerus is a species of marine porcelain crab found in the eastern Pacific Ocean. It is commonly known as the flattop crab. It is a flattened, rounded animal, with a carapace up to 20 mm (0. 8 in) across. It is a filter feeder, and also sweeps food from rocks.

Petrolisthes eriomerus. Retrieved May, 08 2021, from en.wikipedia.org/wiki/Petrolisthes_eriomerus.