silkworm eggs

https://wiki-fusion.win/index.php/How_to_Handle_Silkworm_Eggs_for_a_Successful_Hatch

Silkworm eggs are tiny, pinhead-sized oval dots that start out pale yellow and gradually turn dark blue or black before hatching. Each egg holds the potential for a new generation of silkworms, which will spin fine silk threads for their cocoons. They need careful warmth and humidity to develop, and watching them change color is a quiet little marvel.