I’m dragging this text from when I was talking to a friend about it-

“ usually they’re just outright infertile in terms of eggs- just like duds I guess that just reabsorb into the system. Don’t even have a shell made, just stay as the yoke and reabsorb. but the full moon allowed for it to be fertilized which caused it to go through the system of developing a shell “

Their harpy anatomy is intersex but normally with only one functioning reproductive organ. Full moon did weird magic. Technically it could have happened to either of them but lets be glad it didn’t happen to Maxwell with his tiny hips.