In certain species of dung beetles, researchers have found that knockdown of a gene called orthodenticle not only interferes with horn development but also results in the development of ectopic eye development on the midline of the beetle’s head—in other words, the beetle grows an extra eye. And further study shows that the eye works, to some degree, as researchers found beetles with ectopic eyes and without normal eyes still responded to light. (Photo credit: Eduardo Zattara, Ph.D.)