Gillia altilis, common name the Buffalo pebblesnail, is a species of freshwater snail, an aquatic gastropod mollusk with an operculum in the family Lithoglyphidae.

[4] The operculum is chitinous, oval, yellow to green in color and shows paucispiral markings, with a subcentral nucleus.

This pigmentation is also seen in the nape, the anterior part of the snout, the top of the tentacles, and along the edge of the peristome (the margin of the gastropod shell).

[7] Loss of habitat due to anthropogenic modifications, pesticides and competition with introduced species are considered the major threats to declining or vulnerable gastropod populations in New York State.

[4][5] The New York State Department of Environmental Conservation also reports records from Lake Erie, but gives no references and declares that the current status of this population is unknown.

Its globose shell is adapted for inhabiting high-velocity lotic environments (rheophile animal), because it allows for a large, muscular foot that can suction to rocks.

[6] In New York State, it also commonly inhabits warmwater, shallow lacustrine habitats with mud substrate.

This species lays its eggs in hemisphere-shaped capsules, singly or in clumps up to six at a time, on leaves and stems of macrophytes (or stones and leaf litter).