deuteroconch

English

Etymology

deutero- +‎ conch

Noun

deuteroconch (plural deuteroconches or protoconchs)

1. (zoology) The second chamber of ammonites and other cephalopods
   • 1954, Alan Hilder Smout, Lower Tertiary Foraminifera of the Qatar Peninsula, British Museum (Natural History), page 25:

     A microspheric nucleoconch does not have an obvious deuteroconch, and is followed by a spiral nepionic stage, no matter what the adult chamber arrangement may be.