Many people like to collect the shells of hermit crabs because most hermit crabs live in empty shells left by other small animals. If the shells of hermit crabs are taken, they will immediately find a new "house" to continue living.
Snails are different, they only have one shell in their lives, leaving the shell on their back means death, so how did the shell of the snail come from? How is it different from the shells of other animals?
There are about 43,000 different species of snails in the world, and the snails we are familiar with live on land or in ponds, but there are still some snails that live in the ocean. Some snails reproduce by mating normally, while others are hermaphrodites.
They all have one thing in common – they all hatch from eggs. In general, snail eggs will lay in loose soil or be fixed in rocks. Although some are oviparous (meaning the eggs hatch inside the mother).
When the snail is in the mother, the shell begins to form. The "mantle membrane" is an important organ owned by mollusks such as snails, and its function is to synthesize the shell on the back. Calcium carbonate is the main component of snail shells (although small amounts of protein are also mixed in). Therefore, in order to build the back shell, the mantle membrane generates an electric current that helps to transfer calcium ions into the shell.
Before the snail hatches, the baby snail grows a primordial conical shell. Once the baby snail leaves the snail egg, food is particularly important. Snails instinctively swallow freshly cracked eggshells to replenish calcium. Snails of all ages need to continue to eat calcium-rich foods. This is also one of the reasons why mollusks are considered pests, and spinach, broccoli, and radishes are all rich in calcium and may become a major source of food.
As calcium is replenished, the shell rotates around the original cone. Unlike turtle shells, snail shells contain no nerves and blood vessels, and these shells are actually equivalent to the ribs, vertebrae, and pelvis of the human body. When the shell ruptures, the body renews cells to repair the damage.
Of course, having a self-healing shell doesn't guarantee absolute safety. Many birds like to eat snails because snail shells contain a lot of calcium. There is a deep-sea snail Chrysomallon squamiferum whose back shell is covered with ferrous sulfides, showing a strange metallic appearance in order to confuse enemies.