Like other members of the Spectamen genus, S. geruloides has spiral cord patterns on its shell. It is characterized by broadly rounded cords, intervals with multiple spiral lirae, and weakgrowth lines, and can be distinguished from the similar S. gerula by its smaller protoconch and greater number of spiral lirae. It can vary in color, but adultshells are typically yellowish-white with axialstripes in shades of brown. Protoconchs are yellowish-white at the apex and otherwise yellowish-brown, while juvenile shells are entirely yellowish-brown. As of 1987, the largest known specimen had a length of 7.7 mm and a diameter of 8.1 mm.