How do non-mammals get their adequate calcium?

Question

Seeing as they don't drink milk.

Answer 1

A non-mammal must be non-placental too. Therefore non-mammals are not as developed as mammals when their born. They get their calcium from their eggs normally. But a few odd cases like caecilians actually chew on their mothers skin. Centipedes eat their shed skin.

Answer 2

Earthworms and bones are good sources.

Answer 3

Seeing as most mammals don't drink milk after infancy either, the question applies just as much to them as it does to other creatures. Your calcium needs don't cease to exist when you are weaned. ;)