[astronomy-to-zoology]

Dromiidae

(Sponge Crabs)

Dromiidae is a family of crabs noted for their habit of putting a live sponge onto their “backs” to use as a shelter or camouflage. they hold them in place with a pair of modified back legs which bend upwards. Once the sponge is on the crab the crab will actually trim the sponge to fit the crabs needs using its claws, this is no harm to the sponge and actually benefits it as the sponge can get new bits of organic material from the waterstream as the crab moves around. it also looks like the crab is wearing a huge beanie.

Phylogeny

Animalia-Arthropoda-Crustacea-Malacostraca-Decapoda-Brachyura-Dromiidae

Source,Source