Discovery News has a short article about Australian archaeologist Katherine Szabo’s analyses of tools made of shell instead of stone in Late Pleistocene contexts:
In published research to date, Szabo reports having excavated shell tools dating back 32,000 years from a cave site in eastern Indonesia, and comparing them with stone tools from the same cave.
"It transpired that the shell tools were in fact much more complex to produce than the stone tools," she said.
The stone tools were randomly chipped, but the shell tools had been carefully chosen and shaped.
In one case, a "cats eye" or operculum shell was flaked systematically with five blows, each one slightly overlapping with the last in a clockwise direction.
I want to mention along with this story that one of our own Ph.D.’s, Kildo Choi, published a paper in 2007, “Shell tool use by early members of Homo erectus in Sangiran, central Java, Indonesia: cut mark evidence”. That paper documented cutmarks on early Pleistocene faunal elements that were made by clamshell, not stone. So the use of shell as a raw material probably goes back hundreds of thousands of years in the area.