Young Brunette Girl Reveals Her Seashell Necklace And Tan Lines In The Sand On The Rocky Beach

When the word "seashells" is used to refer only to the shells of marine mollusks then studying seashells is part of conchology. Conchologists or serious collectors who have a scientific bias are in general careful not to disturb living populations and habitats: even though they may collect a few live animals, most responsible collectors do not often over-collect or otherwise disturb ecosystems.
When studying the whole molluscan animal is included as well as studying the shell, then the study is known as malacology; a person who studies mollusks is known as a malacologist.