Margarella expansa is a species of sea snail, a marine gastropod mollusk in the family Calliostomatidae.

It is shining, of a light olivaceous tint or somewhat tinged with pink.

The large body whorl is rounded at the periphery and a little impressed or margined below the suture.

The large aperture is rounded and angular above, green and iridescent inside.

[5] This marine species occurs off the Falkland Islands and in the Straits of Magellan at depths between 0 m and 150 m.