gemmule
gemma

When the environment becomes less hostile, the gemmule resumes growing.

Charles Darwin used the term Gemmule to describe a microscopic unit of inheritance, and what would later become known as chromosomes had been observed separating out during cell division by Wilhelm Hofmeister as early as 1848.

When a gemmule germinates, the archeocytes round the outside of the cluster transform into pinacocytes, a membrane over a pore in the shell bursts, the cluster of cells slowly emerges, and most of the remaining archeocytes transform into other cell types needed to make a functioning sponge.