Spiny Slipper Limpet Shell, Bostrycapulus latebrus 

Spiny Slipper Limpet Shell, Bostrycapulus latebrus. Shell collected off the beach in Los Cabos area, Baja California Sur, May 2020. Size: 2.0 cm (0.8 inches) x 1.4 cm (0.6 inches).

Spiny Slipper Limpet Shell, Bostrycapulus latebrus. Shell collected off the beach of Punta Chivato, Baja California Sur, May 2025. Size: 1.8 cm (0.7 inches) x 1.3 cm (0.5 inches) x 0.5 cm (0.2 inches). Collection, photographs and identification courtesy of Colin Campbell, DVM, Punta Chivato.

Spiny Slipper Limpet Shell, Bostrycapulus latebrus. Shell collected off the beach of Punta Chivato, Baja California Sur, May 2025. Size: 2.3 cm (0.9 inches) x 1.5 cm (0.6 inches) x 0.7 cm (0.3 inches). Collection, photographs and identification courtesy of Colin Campbell, DVM, Punta Chivato.

Spiny Slipper Limpet Shell, Bostrycapulus latebrus. Shell collected off the beach of Punta Chivato, Baja California Sur, May 2025. Size: 2.5 cm (1.0 inches) x 1.9 cm (0.7 inches) x 0.8 cm (0.3 inches). Collection, photographs and identification courtesy of Colin Campbell, DVM, Punta Chivato.

The Spiny Slipper Limpet, Bostrycapulus latebrus (Collin, 2005), is a gastropod mollusk that is a member of the Calyptraeidae Family of Cup-and-Saucer and Slipper Limpet Shells. They are also known as the Obscure Slipper Limpet Shell and the Prickly Slipper Limpet Shell and in Mexico as Pique Espinoso. The shell has an oval to circular profile that is moderately arched, the apex is curved to one side, the exterior of the shell is sculpted with rows of scales or spines that spiral from the apex, and the shelf covers about one half of the shells interior and may be notched at either end or in the center. The exterior color of the shell is a yellowish brown or gray brown, and some have darker brown bands. The interior may have brown spots or blotches and the shelf is white. The Spiny Slipper Limpet Shells reach a maximum of 3.8 cm (1.5 inches) in length and 2.7 cm (1.0 inches) in height.

The Spiny Slipper Limpet is found found attached to rocks and shells in the intertidal zone to depths up to 79 m (260 feet).  They are a subtropical Eastern Pacific species that have a very limited range in Mexican waters of the Pacific Ocean. They are endemic to the southern half of the Sea of Cortez ranging from Mulegé to Cabo San Lucas, Baja California Sur.

Synonyms: Calyptraea echina, Calyptraea hystrix, Crepidula aculeata, Crepidula californica, and Patella aculeata.