Why do some people call money 'CLAMS' ie "you owe me 50 clams"?

Question

where does this come from?

Answer 1

The American Indians used to use clam shells to make Wampum - something they would use as a form of money.

So...You owe me 50 clams, buddy! :-)

Orion

Answer 2

There is, or was, an American comic strip called "B.C." whose regular characters were cave men. They used clam shells as money.