Nearly all mollusks have shells. Most mollusks also have organs called mantles. The mantle is thin and a bit like skin. In a snail, it lines the shell. A snail, like most other mollusks, uses its mantle to make its shell.

To make a shell, the mantle releases a liquid made up of shell materials. Gradually the liquid hardens and forms the shell. Over time, the mantle releases more of this liquid. This in turn adds to the size of the shell.

Snail shells come in many different shapes and sizes. Most snails have spiraled shells, like this tree snail. Some sea snails have shells that coil into cones. Other snails even have shells that are shaped like macaroni.

A snail crawls into its shell when it senses that an enemy is nearby. Remember, a snail is very slow. So it usually can’t escape from an enemy, such as a snake, a frog, or a bird. That’s where the shell comes in. It protects the snail from enemy attack.

Once safely curled up inside, snails can close off their shells. Different kinds of snails do this in different ways. One kind moves the hard part of its foot over the shell’s opening. Another kind spreads a layer of hardened slime over the opening. With the shell opening sealed off, the snail is safe from most attacks. It can stay sealed up like this for days or even weeks.

During long periods of heat or cold, snails may also curl up in their shell to stay moist. They hardly move and need little food or water. This state is similar to how a bear hibernates. When snails go though this process, it’s called estivation (ehs tuh VAY shuhn).

Yes, like most other snails, a land snail lays eggs. Most land snail eggs are very small. They are about the same size and shape as this: O. Over a few days, a land snail may lay around 100 eggs. But most of these eggs are eaten by predators.

A land snail lays its eggs in a small hole it digs in the soil. It covers the eggs with a mixture of dirt and slime. After about two to four weeks, the eggs hatch. The tiny newborn snails have very big appetites. They eat whatever is nearby—including what’s left of their eggshell. Some newborn snails will even eat other unhatched eggs.

Life is not easy for young snails. Very few snails live to be a year old. Most are killed by predators such as birds, beetles, and fish. Young snails that survive the tough first year still have some growing to do. They don’t become adults until they are about 2 years old.

Many sea snails, like the queen conch, lay their eggs on the floors of tropical oceans where they live. Some sea snails lay thousands of eggs over a few days. In fact, the queen conch can lay over 500,000 eggs at one time. But, like land snail eggs, most of these eggs are eaten by predators.

However, many queen conch eggs do hatch, and some of these young snails live long enough to become adults. An adult queen conch is one of the largest snails. It may grow a shell that is 1 foot (30 centimeters) long.

Periwinkles are a group of sea snails. There are many kinds of periwinkles, including the flat periwinkle, the checkered periwinkle, the marsh periwinkle, and even the zebra periwinkle. The common periwinkle lives along the shores of northern Europe and the Atlantic coast of North America. The average periwinkle is about 1 inch (25 millimeters) long and 3/4 of an inch (19 millimeters) wide.

Different kinds of periwinkles live on different parts of the shore. Some periwinkles live near the high-tide line. Others make their homes near the low-tide line. At low tide, when the water goes out, some periwinkles coil up inside their shells to stay moist. This also keeps them safe from predators. When the water returns at high tide, the periwinkles come out from their shells to graze on algae and tiny plants.

Whelks are large sea snails with hard, spiral shells. The knobbed whelk of the Atlantic coast can grow 8 inches (20 centimeters) long. The whelk often eats other mollusks.

A whelk’s main diet is clams. And whelks are experts at opening up a clam’s shell. First, a whelk grasps the clam in its foot. Next, it rubs its shell on the clam until the clam’s shell chips or cracks. Then the whelk slowly pries the clam apart until the clam’s body is exposed. Whelks eat the remains of dead animals, too.

Snails are of the order Gastropoda of the phylum Mollusca. The common edible snail is Helix pomatia.