Scientific name: Littorina littorea
It measures between 2.5 and 3 cm. They live attached to the rocks that are submerged, in the cracks and crevices that serve to protect them from the waves and currents. It feeds on algae and does not neglect small invertebrates when the opportunity presents itself.
They are very resistant mollusks and can last a long time out of the water. When they feel attacked they take refuge inside the shell.