Shell large (up to 9 mm diameter), transparent and completely colorless, smooth, thin-walled and fragile (e.g., in the fifth whorl, the shell thickness is about 10 µm - compared with about 25 µm in Atlanta peroni). Keel high; higher and deeper penetrating between the last whorls than in Atlanta peroni. Keel base not pigmented. Spire of about 3 and 1/2 whorls. Eye lenses very large in adult specimens. Radula large, number of tooth rows limited (to about 70). Radula shows sexual dimorphism (like Atlanta peroni). Larvae of Atlanta fragilis and Atlanta peroni cannot be distinguished by shell shape. If it has not been overlooked in the Pacific or Indian Oceans, Atlanta fragilis appears to be restricted to the Atlantic Ocean, where it is rare by comparison with Atlanta peroni.
See the family Atlantidae for a discussion of the species groups.