They develop very rapidly in their last couple days so the 15 day embryo is a long way from the 21 day hatchling: https://www.nature.com/articles/s41598-024-720

They develop very rapidly in their last couple days so the 15 day embryo is a long way from the 21 day hatchling: https://www.nature.com/articles/s41598-024-72004-y/figures/2 https://www.nature.com/articles/s41598-024-72004-y/figures/2