How big? Way smaller than a BB. the microclots start out as two red blood cells sticking together and then “conglomerate” or “coagulate” from there. When they get enough together to slow blood flow in the brain that’s when brain fog starts. Goes down hill from there.
No, not that small. He could take photos of the clots. The were long (length of a leg) probably 1/4-1/2 inch in diameter. Part of the clot was a true blood clot, the rest was rather like a synthetic rope.