Why do some fish have bones in their eyes?
Great question! I assume you're referring to the sclerotic ring, which is present in many groups of animals, including birds, reptiles, amphibians, and fish, as well as the fossils of many dinosaurs.
Their primary function is to support the eye and help it keep its shape- this is especially important for animals which live in very low or very high pressure environments, such as the bottom of the ocean.
(Image: The skulls and x-rays of a variety of species, all of which display a sclerotic ring, by Tamara Anne Franz-Odendaal)
Franz-Odendaal's paper on the subject is quite interesting, as it dives into the evolution and function of the scleral ring.
