Gibbula magus, common name the great top shell, is a species of small sea snail, a marine gastropod mollusc in the family Trochidae, the top snails.

The solid, widely, deeply umbilicate shell has a low-conical shape.

It is whitish or yellowish, painted with zigzag radiating stripes, maculations or lines of pink or rich brown, sometimes so broken into minute flecks as to appear minutely mottled all over, or sometimes lacking markings.

These are swollen, gibbous and radiately plicate beneath the sutures, and with a rim or flange at the periphery.

The entire surface is spirally finely striate.