The maximal shell size of Atlanta lesueurii appears to vary geographically (from 2 mm in Hawaiian and eastern Australian waters to 6 mm in the tropical western Pacific).
The shell is transparent, thin and fragile, with a smooth surface (lacking raised sculpture).
The spire is very small, somewhat elevated and compact, consisting of about 2½ whorls.
Spire sutures are deep, with the result that the whorls are somewhat rounded in profile and can easily be distinguished.
After metamorphosis the outermost whorl enlarges and inflates rapidly and the keel becomes progressively taller, becoming very tall in large adults and having a truncate leading edge.
The keel base and spire sutures are colorless.

Main features for the recognition of this species are the protoconch composed of just 2¼-3 convex whorls, separated by an incised suture and the absence of any ornament.
The first teleoconch whorl expands rapidly and bears a well-developed flange-like keel.
In the largest specimens the final three quarters of the teleoconch separates from the penultimate whorl.

Eyes are type b, with a large lens.
The Operculum is the type b. Radula is type I, with a narrowly triangular shape.

Atlanta lesueurii is the large species in the genus Atlanta, but Atlanta peronii is larger.

Atlanta lesueurii resembles closely Atlanta oligogyra, in which, however, the first whorls are separated by a superficial suture and the shell remains much smaller.

Overview of description:
Maximal shell size appears to vary geographically, between 2 and 6 mm
Shell transparent with a thin, fragile walls
Shell surface smooth; lacking surface sculpture
Spire compact, consisting of about 2½ whorls
Spire sutures incised, enabling distinction of whorls
Keel tall, with a truncate leading edge
Eyes type b; lens large
Operculum type b
Radula type I, narrowly triangular shape
The maximal shell size of Atlanta lesueurii appears to vary geographically (from 2 mm in Hawaiian and eastern Australian waters to 6 mm in the tropical western Pacific). The shell is transparent, thin and fragile, with a smooth surface (lacking raised sculpture). The spire is very small, somewhat elevated and compact, consisting of about 2½ whorls. Spire sutures are deep, with the result that the whorls are somewhat rounded in profile and can easily be distinguished. After metamorphosis the outermost whorl enlarges and inflates rapidly and the keel becomes progressively taller, becoming very tall in large adults and having a truncate leading edge. The keel base and spire sutures are colorless.
Main features for the recognition of this species are the protoconch composed of just 2¼-3 convex whorls, separated by an incised suture and the absence of any ornament. The first teleoconch whorl expands rapidly and bears a well-developed flange-like keel. In the largest specimens the final three quarters of the teleoconch separates from the penultimate whorl.
Eyes are type b, with a large lens. The Operculum is the type b. Radula is type I, with a narrowly triangular shape.
Atlanta lesueurii is the large species in the genus Atlanta, but Atlanta peronii is larger.
Atlanta lesueurii resembles closely Atlanta oligogyra, in which, however, the first whorls are separated by a superficial suture and the shell remains much smaller.
Overview of description:
Maximal shell size appears to vary geographically, between 2 and 6 mm
Shell transparent with a thin, fragile walls
Shell surface smooth; lacking surface sculpture
Spire compact, consisting of about 2½ whorls
Spire sutures incised, enabling distinction of whorls
Keel tall, with a truncate leading edge
Eyes type b; lens large
Operculum type b
Radula type I, narrowly triangular shape
Atlanta lesueurii