Testudinella patina displays the characteristic circular body shape that is typical of the genus. Species within the Testudinella genus are distributed globally. While most are found in freshwater lakes and ponds, there have been eleven species identified in saltwater environments. The lorica of this species features dorsal and ventral plates that are fully fused laterally, resulting in a greatly flattened dorsoventral shape, occasionally approaching circular. The foot is elongated, retractable, segmented, and ends in a cluster of cilia. The mastax is malleoramate. These species are typically found in littoral habitats and possess two frontal eyes. Differentiation among species is based on variations in shape, size, and location of the foot opening, positioning of lateral antennae, and the outline of the lorica in both dorsal view and cross-section. In most species, the foot opening is located ventrally, while in some, it is terminal. The lorica is also dorsoventrally flattened, and the foot shares similar characteristics as described previously.