At the beach, you find an animal with a two-part shell, a muscular foot, and a radula. you conclude that you have found a mollusks.

Yes

At the beach, if you find an animal with a two-part shell, a muscular foot, and a radula you can conclude that you have found a mollusk.

Since they have two-part shell, with muscular foot and are well adapted in the beach they are referred to as bivalve mollusks. Examples are clams, mussels, and oysters. 

halogen, any of the six nonmetallic elements that constitute group 17 (group viia) of the periodic table. the halogen elements are fluorine (f), chlorine (cl), bromine (br), iodine (i), astatine (at), and tennessine (ts).