What is "amphiuridae"

Amphiuridae (commonly called long-armed burrowing brittle stars or burrowing brittle stars) are a large family of brittle stars of the suborder Gnathophiurina. Some species are used to study echinoderm development (e.g. Amphipholis kochii and Amphioplus abditus) and bioluminescence (the dwarf brittle star, Amphipholis squamata).