Could giant fossil oyster contain giant pearl?

Adam Khor

http://www.huffingtonpost.com/2012/06/05/worlds-biggest-pearl-oyster_n_1570608.html

Not that prehistoric pearls are unknown. They have also been found inside giant Inoceramid clams from the Cretaceous.

This is from "Oceans of Kansas" website:

"As noted by Brown (1940) and Kauffman (1990), sometimes small round nodules are found attached to inoceramid shells. They are the remains of pearls that were fossilized along with the clam shell. The nacre or "mother of pearl" luster is not preserved in inoceramid pearls. This is because the pearly, nacreous color associated with true pearls is made up of a mineral called aragonite. In the Smoky Hill chalk, the aragonite is not preserved. Inoceramid shells and pearls have lost the thin inner pearly aragonite layer, and are solely composed of calcite. This also means that some kinds of shells, like those of ammonites, were not preserved because they are composed entirely of aragonite. An 1940 article in the Hays Daily News noted that George Sternberg had donated 50 pearls from the Smoky Hill Chalk to the Smithsonian Institution, and a scientific paper was published on their occurrence (Brown, 1940)"

And here's an article on the fabled Pearl of Allah mentioned by the article above.

http://www.internetstones.com/pearl-of-allah-pearl-of-lao-tzu-pearl-of-lao-tse.html

Rubecula

Pearls are produced by other creatures besides oysters these days so I have often wondered just how many species of bivalves could produce pearls in prehistoric times. It must have evolved somewhere, but I have no idea where or when.

Adam Khor

Ammonoids seemingly produced them too