They really don't know, but won't say exactly.
My mother always said it was from drinking
cold drinks a lot, but that's not right. I've known
a couple of people that have never partaken of
cold drinks or tea or coffee.
I've been "lucky" and only had the one, but
it was a boone and crockett and had to be
busted up to pass it out in little razor sharp
pieces. Looked like a big cockleburr inside
my kidney. Can't even find the words for the
level of pain experienced. I've broken bones
that didn't hurt as bad. Before I knew what was
wrong, I had a spell and had to go to the floor
and had the black and white tunnel vision
you get just before you pass out. I managed
to crawl over to the phone and only got "9""
pressed of the 911 before it instantly and
completely went away. I guess if I were to
give a comparison I'd say to watch the original
Hellraiser movie where the monsters are
embedding the large fish hooks on chains
into the guy's flesh before commencing to
torture him
Good Luck with trying to pass any shards.
Get sat down or securely propped up or
have somebody hold you up so your knees
don't buckle and you end up hitting your
head as you fall or breaking a bone, etc.