Buccinastrum deforme, common name the collared buccinum, is a species of sea snail, a marine gastropod mollusk in the family Buccinanopsidae, the Nassa mud snails or dog whelks and the like.

There exists also at the base of the shell, a large band of a grayish white color.

The columella is strongly arched, and upon all its length is seen a callosity of a yellowish color.

This shell is very different from other species in its form, which is globular, and its color, of a deep violet.

In some specimens the spire is more elongated, and sometimes, within the shell, where it is of a paler violet, are delineated deeper bands.