The cystic nature of a mature teratoma of ovary is seen here in this hemisected tumor mass. The most common tissue element of these teratomas is skin, so large amounts of hair and sebum are produced, leading to a challenging cleanup problem in surgical pathology following dissection of these tumors. If these tumors are mostly solid, then they are often "immature" teratomas with less differentiated tissue and may behave more aggressively. Rarely, there are frankly carcinomatous areas.