The bryozoan Membranipora spawns teeny pinkish eggs that come out as little skirt-wearing doughnuts, but they slowly round up before they cleave. The first two cleavages are equal, but then the embryo commences to cleave unequally, producing tiers of different-sized blastomeres.

Membranipora grows as an encrusting colony of little coffin-shaped zoids on the surface of kelp blades and other things on floats. Ripe colonies are more opaque, even a little pink, and certainly one can see ripe eggs through the zoid body wall under a dissecting microscope. One can leave a section of colony to spawn in an isolated dish, in which case the eggs come out fertilized. I adopted instead the rather brutal procedure of popping ripe zoids with a pair of forceps, but I can't remember at the moment how I got them fertilized after that...