What is a common name of the animal group like to which snails, slugs, clams, and the squid belong?
a. mollusks
b. annelids
c. chitons
d. cnidarians

 the answer is a.Mollusks were among the first inhabitants of the Earth. Fossils of mollusks have been found in rocks and date back over 500 million years. Mollusk fossils are usually well preserved because of their hard shell.

Most mollusks have a soft, skin-like organ covered with a hard outside shell. Some mollusks live on land, such as the snail and slug. Other mollusks live in water, such as the oyster, mussel, clam, squid and octopus. 

i'd think it's paralell

your answer is going to be physical weathering