To test the hypothesis, she spent eight hours rubbing baboon and human tooth samples with grass stalks, which, unlike wooden picks, contain hard deposits of abrasive silica. (discovermagazine.com)
The tiny particles are 1,000 times smaller than the tip of a human hair, and are designed to latch on to atherosclerotic plaques — hard deposits made from accumulated fat, cholesterol and calcium that build up on the walls of arteries and are prone to rupture, producing dangerous clots. (foresight.org)