Agathotoma ordinaria is a species of sea snail, a marine gastropod mollusk in the family Mangeliidae.

The turreted shell has an oblong shape and contains 7 whorls, with the first two being smooth and convex.

The subsequent whorls are also convex and feature 10-11 ribs that subtly blend into the background and are adorned with spiral lirae.

The white outer lip is thickened (incrassate) and slightly sinuate at the top.

[1] This species occurs in the Pacific Ocean from Peru to Northern Chile.