Low tide line, in an inch of water.
 
Veneridae: 38mm Paphia aurea (Gmelin, 1791).
The Golden Carpet-shell is not always yellow inside.
The pictured form is named "mabillei"(Locard, 1886).
A sublittoral species, which prefers waters with a noticeable density of organic matters.
The specimens I found lived in sand banks just offshore the mouth of the harbour,
low tide line, near the head of the jetty.