sporosac

from The Century Dictionary.

• noun In Hydrozoa, a degenerate medusiform person; one of the simple generative buds or gonophores of certain hydrozoans in which the medusoid structure is not developed.
• noun In Vermes, a sporocyst or redia. See Sporocyst .

from the GNU version of the Collaborative International Dictionary of English.

• noun A hydrozoan reproductive zooid or gonophore which does not become medusoid in form or structure. See Illust. under athecata.
• noun An early or simple larval stage of trematode worms and some other invertebrates, which is capable of reproducing other germs by asexual generation; a nurse; a redia.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun botany A hydrozoan reproductive zooid or simple form of gonophore which does not become medusoid in form or structure
• noun zoology An early or simple larval stage of trematode worms and some other invertebrates, which is capable of reproducing other germ cells by asexual generation; a redia.