Button Shell, or Dwarf Olive
Phylum: Mollusca, Class: Gastropoda, Order: Neogastropoda, Family: Olividae, Genus: Olivella, Species: Olivella biplicata · Olividae (Olive family) · Gastropod, whole shell, oval-cylindrical shape
Species
Olivella biplicata
Shell Type
Gastropod, whole shell, oval-cylindrical shape
Family
Olividae (Olive family)
Size
Approximately 0.5 inches in length, which is average for this species. Adults typically range from 0.4 to 1 inch.
Color & Pattern
Uniform pale white to cream coloration, likely slightly sun-bleached or worn from wave action, displaying a smooth, glossy porcelain-like surface.
Rarity
Very Common, frequently washed up on sandy beaches within its native range.
Habitat
Found intertidally and in shallow subtidal zones, typically buried just beneath the surface of sandy bottoms, sandbars, and protected bays.
Geographic Range
Pacific coast of North America, ranging from Alaska down to Baja California, Mexico.
Description
A charmingly compact, polished, and rounded olive shell featuring a low spire and a distinctively narrow aperture. The surface is smooth and shiny, designed to glide easily through the sand where the living snail burrows.
Key Features
Smooth, glossy exterior, low spire, compressed oval shape, and the characteristic two folds (plica) on the lower inner columella.
Collector Value
Low to moderate commercial value due to high abundance, but heavily collected for craft purposes and localized shell collections. Typical specimens cost very little.
Condition Notes
Good condition overall, though showing signs of slight beach wear and fading to a uniform white. Surface remains intact with no major fractures or deep boring holes.
Interesting Facts
Indigenous peoples along the Pacific coast historically used Olivella shells extensively for currency, beads, and intricate regalia, creating thousands of shell beads traded across vast distances.
Ecological Role
Functions as a sand-dwelling carnivore and scavenger, feeding on detritus and small organisms, while serving as a food source for fish and shorebirds.
Similar Species
Other dwarf olive species such as Olivella baetica, which tends to be smaller, slenderer, and possesses a higher spire.
Beach Finding Tips
Look along Pacific surf beaches at low tide, particularly in sandy troughs and near the wrack line where small shells accumulate after rolling in with the waves.