The spanner in the works here is semantics. Probable, and even obvious, tools get rubbished here because, not showing evidence of intentional modification, they are -- strictly speaking -- not artifacts. This may well be true, as far as it goes. But newer people, especially, want to know if their stuff was used for some purpose(s) -- not whether it was modified.
Classic case in point : "Indian marbles." Rarely (if ever) modified. But, in many cases, no-brainier tools. Tube pipes, in particular, cannot be used without them. Without a round pebble just the least bit smaller than the tube's inside diameter to keep the smoking mixture where it belongs (and out of your mouth) but letting the smoke through around the edges, no dice. The tube and the pebble were one functional unit.
