Dwarf Surf Clam or Little Bean Clam
Phylum: Mollusca, Class: Bivalvia, Order: Venerida, Family: Cardiidae, Genus: Trachycardium, Species: trachycardium · Cardiidae (Cockle family) · Bivalve (two-shelled), whole shell, fan/oval shape
Species
Mulinia lateralis (or similar small venerid/carditid bivalve)
Shell Type
Bivalve (two-shelled), whole shell, fan/oval shape
Family
Cardiidae (Cockle family)
Size
Approximately 0.5 inches (12-15 mm) wide, which is average for juvenile or smaller species in this family. Adults of similar small bivalves typically range from 0.3 to 1 inch.
Color & Pattern
Uniform creamy white or pale ivory coloration with subtle glossy sheen. No distinct color banding is visible, likely due to natural pigmentation or minor bleaching from wave action. The interior matches the exterior in tone.
Rarity
Very Common, frequently washed up on sandy beaches worldwide.
Habitat
Shallow subtidal to intertidal zones, typically found buried in fine sand, mudflats, or seagrass beds in marine environments.
Geographic Range
Common along the Atlantic and Gulf coasts of North America, as well as various temperate to tropical marine waters globally depending on the exact minor bivalve species.
Description
A small, sturdy bivalve shell characterized by its rounded, somewhat triangular outline and prominent radial ribs radiating from the umbo to the ventral margin. The surface exhibits distinct, regular ridges giving it a textured, corrugated feel. The margin is finely crenulated to match the external ribs.
Key Features
Prominent radial ribs, equivalve rounded shape, distinct umbo pointing anteriorly, and a crenulated margin matching the external ribbing.
Collector Value
Low commercial value due to high abundance, but appreciated by beginner beachcombers and micro-shell collectors.
Condition Notes
Good condition. The shell is fully intact with no major fractures, though it shows minor smoothing from wave wear. Color is uniformly white due to weathering. Collectibility grade is Good.
Interesting Facts
Many small bivalves serve as a crucial food source for migratory shorebirds and bottom-feeding fish. Their ribbed designs help stabilize them in shifting sands.
Ecological Role
Acts as a primary consumer feeding on phytoplankton via filtration, while serving as a vital prey base for carnivorous snails, crabs, fish, and shorebirds.
Similar Species
Various small species of cockles (Cardiidae) and cross-barred venus clams (Chionopsis), distinguished primarily by subtle differences in hinge teeth, rib count, and overall outline shape.
Beach Finding Tips
Look in the wrack line on high-energy sandy beaches, particularly after a storm or during low tide when fine sediments are deposited.