Ned Heite wrote:

><<snip>>
>On a shell midden near St. Michaels Md., we found lots of oyster
>shells with the characteristic sharp break, but also lots of angular
>hammerstones. In this land of water-washed round rocks, an angular
>rock is regarded as an artifact. Indeed, it seems that the Indians
>made oyster knives out of cobbles to impart that sharp break.

And obviously we call these stone tools "oyster crackers"

Silas Hurry
Historic St. Mary's City
where "Dead Oysters Talk"