RAINFLOW 15oz Chick Grit with Calcium - 20-40 Mesh Limestone Grit for Chickens and Ducks, Natural Poultry Digestive Support for Young Chickens & Egg Layer Hen for Strong Eggshells

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Bird Cuttlebone for Parakeets Cuttlebone for Birds - Natural Cuttlefish Bone Bulk Chew Toy Bird Bites Calcium Stone for Canaries Tortoises,Snails,Reptiles,Parrots,Cockatiel

comments:

One-plankton- posted on r/isopods34w

I think cuttlebones are going to be the cheapest route, here’s a listing on Amazon for 20 at 1$ a piece. ETA: another option is chicken grit limestone

Bird Cuttlebone for Parakeets Cuttlebone for Birds - Natural Cuttlefish Bone Bulk Chew Toy Bird Bites Calcium Stone for Canaries Tortoises,Snails,Reptiles,Parrots,Cockatiel