The Blue Sponge (Haliclona sp.) is a peaceful filter-feeder that requires an established tank to thrive. As their name suggests, they have a blue coloration, though they can become faded if stressed. They encrust over rock and do well with moderate flow. They are sensitive to fluctuations in parameters and should not be exposed to air. They should not be kept with fish not suitable for reef tanks, such as puffers or triggers.