A mollusk's exoskeleton is composed of chitin (a component of the exoskeleton of most animals) and conchiolin which is a form of calcium carbonate (present in snail shells). These complex proteins are secreted by the mantle layer present right below the shell and hardens over time as the creature grows.
Mollusks do not have a spiny or leathery covering; instead, they typically possess a hard external shell made of calcium carbonate, which can be smooth or textured. Some mollusks, like octopuses and squids, lack a traditional shell and have a more flexible body structure. The shell serves as protection for many species, while others rely on camouflage or other adaptations for defense.
All mollusks possess a soft body covered by a hard shell, a muscular foot for movement, and a mantle that secretes the shell. These characteristics distinguish mollusks from other phyla in the animal kingdom.
Mollusks have soft body and hard shells but some don't even have shells.
no..... slugs are mollusks and they don't have a shell
Most of Mollusks protect themselves with help of shell . Shell is hard protective covering made up of CaCO3. Cephalopods are not protected by shell .
The hard shell of a lobster is known as the chitin.
Mollusks without backbones are called invertebrates. Some examples of invertebrate mollusks include snails, clams, octopuses, and squid. These animals have soft bodies and are protected by a hard external shell or by their muscular structure.
545 million years ago
Protect against predators trying to eat it.
The hard shell protects the very soft body of the mollusk.
I assume calm means clam? In which case, a clam does have a hard external (skeleton?) shell of calcium carbonate. The shell is known as an exoskeleton.
A crab has an external hard shell, and is an invertebrate.