Agathistoma fasciatum (known commonly as the Smooth Atlantic Tegula) is a species of sea snail, a marine gastropod mollusk in the family Tegulidae.

[2] A. fasciatum is slightly smaller than T. lividomaculata, which is 5⁄8 to 7⁄8 in (16 to 22 mm) high, and somewhat wider than that.

The columella is short, arcuate, with a white callus above and two transverse tubercles at its base.

The color of the shell is reddish or pale tan to dark brown, usually with irregular, axially distributed splotches of white, and fine spiral lines of alternating reddish and white spots or streaks.

[3][4] A. fasciatum often lives under rocks at low tide level, and is abundantly found throughout southern Florida, the Caribbean Sea and the West Indies (Atlantic Ocean)[3] at depths between 0 m and 90 m.