Panacea glicimeris (Linnaeus, 1758) is a species of fossil Geoduck, a marine bivalve mollusk . This specimen is 9 x 6 x 3,5 cm! In the second picture an actual Geoduck. Panopea sp., geoduck clam fossil dating from between 1.5 million years ago to .75 million years ago commonly found at low tide in littoral (sandy and muddy bottom) or sub-littoral (open bay, muddy marine) zones. Fossil specimen is oval-shaped. Top and bottom shells of clam are still attached at the ligament. Growth rings are visible, but not easily detected due to its uneven surface. Matrix still present inside. From an old collection. Rare of this size.