Ilia nucleus is a marine crustacean. The small species has a globular cephalothorax and long, slender legs. The cephalothorax is typically around 2.5 cm in diameter. Due to the shape of its body it is also called the pebble crab. Typical of its genus are the straight, cylindrical claws in which the dactyl (the moving finger) is longer than the manus (the palm of the claw). Its upper side is coloured strongly orange or red, whereas the underside and parts of the legs are white.
The species inhabits rocky, sandy or muddy ground in dephts of up to 80m and is found in parts of the mediterranean sea, including Greece, Italy, Turkey, southern France and Croatia.
