how are seashells made?

Answer 1

Sea shells are made by animals called mollusks. Mollusks include snails (one shelled animals) and clams, oysters (two-shelled animals), as well as octopus and squid (interior shelled animals).

What we call sea shells are the first two kinds.
These organisms have what is called a "mantle", a structure in their bodies that secrete a substance usually made of calcium carbonate that turns into the hard shells that cover their bodies. When these organisms outgrow their shell, they leave it and grow another one. When they die, their soft body parts deteriorate and the shells then are left behind to wash up on the beach. Each species of mollusk makes its own kind of shell and is distinctive from the shells of other species.

Biology Teacher

Answer 2

excto skeletons

they all belong to the snail family, The Class Gastropoda, the Snails: are divided into two Subclasses: Prosobranchia and Opisthobranchia,

The Subclass Prosobranchia: In turn divided into three living Orders: Archaeogastropoda, Mesogastropoda and Neogastropoda. Or Marine, freshwater and terrestrial. Sea Shells are the hard exto skeletons of the Archaeogastropoda snails.

A shell is the hard, rigid outer covering, or integument, of certain animals. More specific scientific names include exoskeleton, carapace, and peltidium. A shell may be made of nacre (a combination of calcium and protein), chitin, bone and cartilage, or silica.

While many sea animals produce exoskeletons, usually only those of molluscs (also spelt "mollusk") are normally considered to be "sea shells". The majority of shell-forming molluscs belong to the classes Gastropoda (univalves, or snails) or Bivalvia. Three other shell-bearing classes are Scaphopoda (tusk shells), Polyplacophora (segmented chitons) and Monoplacophora (single-shelled chiton-like animals, also called Tryblidia). Some species of Cephalopoda also build shells, including the primitive Nautilus order which produces the famous "chambered Nautilus" shell; although some taxa of cephalopods such as octopuses and squid only form small internal shells.

The shell will grow over time as the animal inside adds its building material to the leading edge near the opening. This causes the shell to become longer and wider to better accommodate the growing animal inside. A mollusc shell is formed, repaired and maintained by a part of the mollusc called the mantle. Injuries to or abnormal conditions of the mantle are often reflected in the shell they form and tend. When the animal encounters harsh conditions which limit its food supply or otherwise cause it to become dormant for a while, the mantle often ceases to produce the shell substance. When conditions improve again and the mantle resumes its task, a "growth line" which extends the entire length of the shell is produced, and the pattern and even the colors on the shell after these dormant periods are sometimes quite different from previous colors and patterns. Interestingly, each species of mollusc animals will build the external shell in specific shape, pattern, ornamentation, color which genetically governed. However if you examine each shell from same species, no one is identical. For human, the thumb print is uniquely an identity differentiation; what then is the identity differentiation for mollusc animals?

The majority of shells are made of nacre, an organic mixture of outer layers of horny conchiolin (a scleroprotein), followed by an intermediate layer of calcium carbonate (CaCO3) as either calcite or aragonite in the form of platy crystals. Shells of the class Polyplacophora are made of a softer calcium carbonate compound called chiton.

Answer 3

A shell is the hard, rigid outer covering, or integument, of certain animals. More specific scientific names include exoskeleton, carapace, and peltidium. A shell may be made of nacre (a combination of calcium and protein), chitin, bone and cartilage, or silica.

You could get more information from the link below...

Answer 4

It is almost like rings on a tree the animal secretes a calcium rich deposit on the edge of its shell and over time the shell expands

Answer 5

Ask her - She sells sea shells by the sea shore...

Kidding! Calcium, actually - formed by the shell's occupant