It seems that there are two kinds: the "rootless" kind that slip out easily, and the Pili multigemini, which hurt.
-- Sean
I get both as well. Both types appear consistently and I get a fair amount of them... probably why blades only last about 2 shaves for me! With the pili there are usually about 8-10 all together. Those rootless ones... man I can't believe how thick they are!