This large Thorny Oyster shell (Spondylus) is from an old collection from the 1960s. It measures 5 1/2" wide, 5 1/4" deep and stands about 4 1/2" tall (bottom of base to top of worm tube which is on top of shell). Measurements include spines. This amazing specimen has all kinds of neat sea things on it, including worm tubes, clam shells, coral, and barnacles.  As you can see in the last photo, the thorny oyster shell naturally attached and grew from the flat rock at the base! This shell weighs over 1 pound! Super unusual specimen to add to any collection or display. Winning bidder adds $12.00 shipping in the US.