Sources : Pina

Thomas of Cantimpré [circa 1200-1272 CE] (Liber de natura rerum, Fish 7.63): The pina likewise belongs to the genus of shellfish, as Pliny says. It has a round body. Male and female travel together. The pina opens its shells to the moon and offers itself as if it is dead to the little fish. Those immediately rejoice, they are emboldened by this permission, and enter the pina's shell. As soon as the pina feels itself to be full, it takes hold of whatever it has enclosed, and gives a portion to his companion. This is a clear indication that there is a sense in the aquatics. - [Badke translation/paraphrase]