Add all cell types from Musser at al

[cmungall]

https://www.science.org/doi/10.1126/science.abj2949

The evolutionary origin of metazoan cell types such as neurons and muscles is not known. Using whole-body single-cell RNA sequencing in a sponge, an animal without nervous system and musculature, we identified 18 distinct cell types

v interesting paper see summary here:
https://www.nature.com/articles/d41586-021-03015-2

neuroid cells are hypothesized precursors to neural cells, they communicate with digestive cells