The island also possesses some uncommon invertebrates - the major survey in 1905-1906 discovered species new to science. Among these were three species of earthworm (including "Henlea hibernica"), a bristletail ("Praemachilis hibernica") and a mite ("Trachyuropoda hibernica"). The earthworm aspect of the study found 34 species, of which 18 were previously unseen in Ireland, including the three new to science as a whole, and noted that the average size of specimens was smaller than on the mainland by a material amount. A degree of local variation was also noted, and for example, one type was particularly prominent near the Raven's Well.