Cuttlebone

Cuttlebone is a natural, calcium-rich supplement commonly used to support healthy exoskeleton development in isopods, snails, and other invertebrates. Simply place a small piece in your enclosure, and your colony can graze on it as needed.

It is soft enough for them to eat as a whole so you don't have to worry about shaving it or making it into a powder like you do with limestone chunks. Once they eat the "meat" of it and leave the little flat shell behind, just toss it out and replace it with a new one.

These are nice pieces of cuttlebone. They're about 3-4" long and rather thick.