The egg. But it looks like phylotypic animal body plans may have originated in cell aggregates before the development of the egg: https://onlinelibrary.wiley.

The egg. But it looks like phylotypic animal body plans may have originated in cell aggregates before the development of the egg: https://onlinelibrary.wiley.com/doi/epdf/10.1002/jez.b.21417 https://onlinelibrary.wiley.com/doi/epdf/10.1002/jez.b.21417