Some microphotos I took of Limulus (horseshoe crab) embryos in their shells (click for full-size images). Each sphere was about 1/4 of a centimeter wide.
Thanks to Jamin DeProto, microscope-meister at MBL and Harvard Med School, for helping me to learn how the equipment worked. The last image won 1st Prize in the 1998 MBL microphotography contest. (Jamin won the Grand Prize for his pollen images.)