Cookia sulcata, or Cook's turban, is a species of large sea snail, a marine gastropod mollusc in the family Turbinidae, the turban snails.

The seven whorls are well rounded, with close lamellose incremental striae, and corrugated by obliquely descending subtuberculose folds.

The base is flattened bearing concentric densely squamose lirae, deeply concave in the center, and indented in the place of the umbilicus.

The umbilical region and part of base is covered with a thin callus.

The median tooth of the radula has a long basal plate and a short body.