Specimens and eggs masses of the gastropod Trochita pileus were collected during a research cruise by bottom trawling at depths between 82 m and 120 m. Adult T. pileus were found attached to such hard substrata as the shells of scallops and oysters. The egg mass of T. pileus is composed of 7–8 transparent, triangular-shaped egg capsules fixed to the substratum with stalks. Four egg masses collected from brooding females, with a total number of 241 embryos, were examined. Trochita pileus is a protandrous hermaphrodite, and histological studies of the male, transitional, and female gonads were performed. The testicular portion of the gonad in both male and transitional individuals and the ovary of the female were studied by histological techniques. Spermatogenesis was observed for males and transitional individuals.