Over the weekend, my wife and I went to one of our favorite restaurants for dinner. We ordered the fried calamari for our appetizer, as we usually do. In my first mouthful, I thought I crunched on some sand - no problem, I thought, it's seafood, so not all that unusual. But there was more crunching. I stopped chewing and pulled out a 1/4 inch more-or-less round, thin, flat piece of what I thought was glass. I notified one of the owners, and after some investigation, I was told that the squid was not cleaned properly, and a piece of the cartilage made its way thru to plate.
Plausible explanation? I have never experienced this before, and I was just wondering if the cartilage, when cooked, could appear to be glass-like.