The Egyptians used schist palettes to grind the pigments used to prepare kohl, which had an aesthetic as well as a pharmaceutical and practical function, since it protected eyes from the reflection of sunlight. The palette here is in the shape of a turtle, of which there were three species known in ancient Egypt. Shells of the Red Sea turtle (Chelonia imbricata) were used to fashion delicate combs, and those of the tortoise (Testudo kleinmanni) in making lutes. Freshwater turtles (Trionyx triunguis) were eaten. In certain cosmogonic texts, the animal personified Geb, the god of the Earth.