Teredo navalis

from The Collaborative International Dictionary of English v.0.48

Inclusa \In*clu"sa\, n. pl. [NL., fr. L. inclusus, p. p. of
   includere to shut in.] (Zool.)
   A tribe of bivalve mollusks, characterized by the closed
   state of the mantle which envelops the body. The ship borer
   ({Teredo navalis}) is an example.
   [1913 Webster]