The extremely sensitive star-like structure is covered with minute touch receptors known as Eimer's organs. The nose is about 1 cm in diameter with roughly 25,000 Eimer's organs distributed on 22 appendages. Eimer's organs were first described in the European mole in 1871 by German zoologist Theodor Eimer. Other mole species also possess Eimer's organs, though they are not as specialized or numerous as in the star-nosed mole.