Gemmule

(plural gemmules)

(biology) A small gemma or bud of dormant embryonic cells produced by some freshwater sponges1978 Patricia R. Bergquist, "Sponges"
The actual formation of gemmules by fresh-water sponges is so clearly an adaptation to seasonal climatic changes, that at first it was reasonable to believe that seasonal alternation itself induced the gemmulation.
(obsolete) A hypothetical particle once thought to be the basis of heredity