Serpulae

Serpula Ser"pu*la, n.; pl. {Serpul[ae]}, E. {Serpulas}. [L., a little snake. See {Serpent}.] (Zo["o]l.) Any one of numerous species of tubicolous annelids of the genus {Serpula} and allied genera of the family {Serpulid[ae]}. They secrete a calcareous tube, which is usually irregularly contorted, but is sometimes spirally coiled. The worm has a wreath of plumelike and often bright-colored gills around its head, and usually an operculum to close the aperture of its tube when it retracts. [1913 Webster]