Gymnobela agassizii is a species of sea snail, a marine gastropod mollusk in the family Raphitomidae.

It contains eight convex whorls, shouldered, with about sixteen thick, rounded, oblique ribs, separated by concave interspaces.

The revolving lines become stronger and more elevated below the shoulder, and cross the ribs as well as their intervals.

Below this, it curves strongly forward and recedes again at the siphonal canal, which is rather short, narrowed and a little excurved.

[2] G. agassizii can be found in Atlantic waters, ranging from the coast of Massachusetts south to Tobago.