Worms love them, but like corn cobs, they have to become part of worm bin furniture, moving into new bin when you harvest (which isn't a bad thing because they will help innoculate)... Baby worms especially love them to hide in the fur and you will never even see them, much less get them out... They take a really really long time to break down, but they do eventually... If you can drill a hole into the shell before giving it, that speeds things up