Features on the planet Venus are named for women and goddesses. Colles are small hills or knobs, named after sea goddesses. Coronae are oval features of uncertain origin, named for fertility and earth goddesses. Planitiae, low plains, are mythological heroines. Tholi, small dome-like hills, are named for (miscellaneous) goddesses. Valles, valleys, are named according to their length: if more than 400 km, after the word for the planet in various world languages, otherwise after river goddesses.