Common Sundial Shell or similar turreted snail
Phylum: Mollusca, Class: Gastropoda, Order: Littorinimorpha, Family: Pachychilidae, Genus: Brotia, Species: Brotia costula · Pachychilidae (Freshwater snail family) · Gastropod, whole shell, elongate spiral shape
Species
Terebratalia transversa or related turrid/melanid snail
Shell Type
Gastropod, whole shell, elongate spiral shape
Family
Pachychilidae (Freshwater snail family)
Size
Approximately 2 to 3 inches in length, which is typical for adult freshwater gastropods of this type.
Color & Pattern
Dark brown to nearly black periostracum covering the exterior, with a pale whitish or cream-colored interior aperture. Some lighter banding visible near the spire.
Rarity
Common in its native freshwater habitats, but considered uncommon to find in general beachcombing collections due to its freshwater origin.
Habitat
Freshwater rivers, streams, and freshwater lakes, typically found crawling on muddy or rocky bottoms.
Geographic Range
Southeast Asia, particularly tropical freshwater river systems in regions like Thailand and surrounding countries.
Description
An elongated, high-spired freshwater gastropod shell featuring a tapering spire with numerous whorls, a dark fibrous periostracum intact on the surface, and a smooth, oval aperture.
Key Features
Elongated turreted shape, numerous flattened whorls, distinct dark brown periostracum, and a smooth oval aperture without siphonal canals.
Collector Value
Low to moderate commercial value, primarily collected by freshwater mollusk specialists rather than marine shell enthusiasts.
Condition Notes
Good condition with intact periostracum and complete spire. Minor wear at the very tip of the apex, grade is Good to Fine.
Interesting Facts
Many members of this freshwater family are amphibious or live in fast-flowing streams where they graze on algae using a specialized radula.
Ecological Role
Acts as an important algae grazer and detritivore in freshwater river ecosystems, serving as a food source for fish and waterbirds.
Similar Species
Other freshwater gastropods in the families Pachychilidae and Thiaridae, distinguished primarily by sculpture details and geographical origin.
Beach Finding Tips
Not found on beaches since this is a freshwater terrestrial/riverine species; look along the muddy banks and shallows of tropical Asian rivers.