If I seem to be diverting the topic, I apologise but I was wondering.

If you step on a stone fish with typical water/beach shoes will the horns penetrate or will you simply crush the fish?

Around the Canadian coast where I grew up we have fish called sculpins which have horns similar to stone fish. they can be quite small to the length of a forearm from finger tip to elbow in most places though. http://en.wikipedia.org If stepped on they are super painfull and will lay you up for a while but I have never heard of them being fatal. In fact, I have never heard of anyone stepping on one either. They dwell in the rocks and are quite large so they are easy to avoid. Really fun to catch as well. but the horns are super sharp and if you did step on one it most likely would go through the bottom of all but the toughest bottomed shoes.