Which member of the class 'Gastropoda' is in the picture?

Limpets are aquatic snails with a shell that is broadly conical in shape and a strong, muscular foot.

Although all limpets are members of the class 'Gastropoda', limpets are polyphyletic, meaning the various groups which are referred to as "limpets" have descended independently from different ancestral gastropods.

This general category of conical shell is known as "patelliform" (dish-shaped). All members of the large and ancient marine clade 'Patellogastropoda' are limpets. Within that clade, the members of the 'Patellidae' family, in particular, are often referred to as "true limpets".

Some species of limpet live in freshwater, but these are the exception.