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Date: | Fri, 27 Sep 2002 17:40:52 -0400 |
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The largest ostracods actually reach a couple of cm, so 5 mm is not unheard of. They do have calcite shells, but the structure is very different from those of mollusks and similar to the hard parts of certain other crustaceans (e.g., crabs). They are common in marine and freshwater habitats; a few get into humid terrestrial areas.
Identification of ostracods and other bivalved crustaceans versus mollusks is very easy with the animal present. However, it can be more tricky with just the shell. The muscle scars, hinge, and growth pattern are useful indicators, but some Cambrian fossils remain somewhat uncertain in assignment.
Dr. David Campbell
Old Seashells
University of Alabama
Biodiversity & Systematics
Dept. Biological Sciences
Box 870345
Tuscaloosa, AL 35487 USA
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That is Uncle Joe, taken in the masonic regalia of a Grand Exalted Periwinkle of the Mystic Order of Whelks-P.G. Wodehouse, Romance at Droitgate Spa
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