The Collaborative International Dictionary of English v.0.48:

Squilla \Squil"la\ (skw[i^]l"l[.a]), n.; pl. E. Squillas
   (-l[.a]z), L. Squillae (-l[=e]). [L., a sea onion, also, a
   prawn or shrimp. See Squill.] (Zool.)
   Any one of numerous stomapod crustaceans of the genus
   Squilla and allied genera. They make burrows in mud or
   beneath stones on the seashore. Called also mantis shrimp.
   See Illust. under Stomapoda.
   [1913 Webster]