Pacific Jewel Box (or Leafy Jewel Box)
Phylum: Mollusca, Class: Bivalvia, Order: Venerida, Family: Chamidae, Genus: Chama, Species: Chama mexicana · Chamidae (Jewel Box family) · Bivalve (two-shelled mollusk); Single valve (likely the upper/right valve); Roughly circular to oval shape.
Species
Chama mexicana (High confidence given the Cabo locality)
Shell Type
Bivalve (two-shelled mollusk); Single valve (likely the upper/right valve); Roughly circular to oval shape.
Family
Chamidae (Jewel Box family)
Size
Approximately 1.5 - 2 inches (38-50mm). This is a medium-sized specimen; adults can reach up to 3-4 inches.
Color & Pattern
Mottled cream and tan base with faint reddish-brown or purple staining near the umbo (hinge area). The interior is typically white with a colored margin. The exterior appears somewhat worn, muting the natural vibrancy.
Rarity
Common (frequently found beachcombing in the Gulf of California, though often worn).
Habitat
Marine; found in shallow subtidal zones attached to rocks, coral reefs, or other shells. They are sedentary filter feeders.
Geographic Range
Eastern Pacific: Southern California through the Gulf of California (Cabo San Lucas) and south to Peru.
Description
A thick, heavy bivalve characterized by a cemented lifestyle. The shell surface is sculpture with irregular, leafy or scale-like projections (foliations). This specific specimen is the upper, non-attached valve, showing a flattened, slightly convex profile with visible concentric growth lines and eroded spines.
Key Features
Heavy, thick valves; irregular leafy sculpture; a distinctive 'dentition' or hinge line; the shell is 'fixed' or cemented to a substrate by the left valve.
Collector Value
Low to Moderate ($2-$10 USD). Commonly available, but high-quality specimens with intact, long delicate spines are prized by collectors.
Condition Notes
Fair condition. The shell exhibits significant beach-wear (erosion), which has smoothed down the delicate leafy spines usually present in live specimens. The color is slightly sun-bleached. Grade: Good (Better for study than for show-piece display).
Interesting Facts
Jewel boxes are 'cemented' bivalves; like oysters, they cannot move once they attach to a rock. They are called 'Jewel Boxes' because when the two halves are closed, they can resemble a small, rugged treasure chest.
Ecological Role
Secondary reef builders; they provide micro-habitats for smaller organisms to hide within their spines. They are preyed upon by specialized gastropods like Murex snails.
Similar Species
Chama buddiana (smaller, often more reddish) or Chama arcana (found further north). Distinguished by the specific coarseness of the scales and geographic location.
Beach Finding Tips
Look in rocky tide pools or areas with significant coral rubble after a storm in the Cabo San Lucas region. They often wash up as single valves after the animal dies and the hinge ligament decays.
Notes
Cabo