>>I feared this answer... The problem is simple:
>>Here in Bremen, Germany the harbor was not deep enough
>>and they removed alot of sand & stones from it. In a
>>area near the harbor they deposite that sediments.
>>There i find the fossil...
>>Flintstone in this ice age sediments (when i remember
>>right this city stands on a big sand dune build up in the
>>ice age) is not really uncommon - but it should not really
>>help to determinate the age when i understand it right.

Glaciers mix things around a lot, but it would be possible to find out where the glaciers crossed and what flint-bearing deposits are in that general vicinity.  However, harbors also contain an assortment of ballast stones, picked up by ships around the world whenever they needed a little extra weight.  Thus, the origin of the specimen is pretty uncertain.

Note that some fossil brachiopods can also vaguely resemble cardiids in general shape and sculpture.

    Dr. David Campbell
    Old Seashells
    University of Alabama
    Biodiversity & Systematics
    Dept. Biological Sciences
    Box 870345
    Tuscaloosa, AL  35487-0345 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