Creeping Ancylid Snail (Ferrissia rivularis) is a small (shell length 3.9 mm) freshwater limpet that is distributed throughout most of North America. In New Mexico it has been found in the Ute Reservoir (Quay County), the Rio Grande (Rio Arriba County), and the Colorado River (San Juan County). They attach themselves to rocks and mussel shells in rivers and creeks, or to rocks in exposed habitats in lakes.