As with other big-eared bats, the huge ears of Allen's big-eared bat can be curled back along the sides of the neck so they resemble the horns of a ram. When its ears are tucked out of the way in this manner, one of the cartilage folds of the ear (the tragus) remains erect and may actually look like a small ear, which can make it hard to identify a roosting bat. Learn more about the Idionycteris phyllotis, more commonly known as an Allen's Big-eared Bat, in this easy-to-read species overview by the Smithsonian's National Museum of Natural History.