Snails can be objects of fascination for kids playing outside. Lucky for the snails, they have their hard shells to protect them from children and predators alike. But are they born with that natural armor, or do they have to find it or grow it for themselves?

Snails are, in fact, born with shells, but they don’t initially look like how you might imagine them. Snails are hatched from eggs that are buried beneath the surface layer of the soil or, in the case of marine snails, placed in a protected area, like near a rock. It usually takes two to four weeks for the eggs to hatch and for the baby snails to emerge, shells and all.

The shell of a baby snail, often referred to as a protoconch or “earliest shell,” is colorless and very soft. Due to the fragile state of its shell, a newly-hatched snail needs to consume a lot of calcium, which will help its shell to harden. A baby snail usually begins its calcium-rich diet by eating the shell of the egg it hatched from, a convenient source of nutrients.

As the snail continues to grow, its shell grows with it. The snail produces new shell material, like the soft material of its protoconch, that expands its shell and then hardens. The part of the shell it was born with ends up in the center of the spiral when the snail and its shell are fully grown. As a snail matures, the number of whorls or spirals which its shell has increases, as do the rings that grow inside the shell. Much like the way we think about tree rings, these rings inside a snail’s shell can be used to approximate the age of the snail.