Especially in those gastropod groups with an almost immobile way of life, the simplest construction of eyes can be found. Among those snail groups mainly are the limpets (Patellidae). ... A limpet's cup shaped eye. For their needs, therefore, a simple cup shaped eye is quite enough.

Do limpets have a brain?

The "brain" of limpets consists of a relatively small number of neurons, and it is not clear how they find their way home. Like other archaeogastropods, male and female limpets look much the same, and can be distinguished only by the color of the gonads and microscopic examination of their sex cells, or gametes.

Can limpets see?

In life, many limpet shells are often covered in microscopic growths of green marine algae, which can make them even harder to see, as they can closely resemble the rock surface itself.