[nly]

Pyrex will shatter if you take it out of a blistering hot oven and pour cold water on it (e.g. to let stuck on food soak).

[yyyyyak]

Yah...I just learned this the hard way. I took it out of the oven and put in on the cold granite countertop.

[govspy]

I never said that Pyrex is unbreakable. But it certainly wont break just because "an ignorant person left it in the oven for hours on end".

Almost every material known to man will break/crack/shatter/do-something if you rapidly cool it from an elevated temperature.

[d2xdy2]

Yeah, taking a piping hot casserole dish out of the oven and placing it on a damp rag on my counter showed me this feature. Pretty terrifying at the time.