CHINESE WATERCHESTNUT A.K.A WATER CALTROP

I saw these stuff at every produce market in Chinatown, Chicago last month. We missed the Chinese Moon Festival by a day, i thought i could still buy moon cakes but to no avail, i instead ended up buying these. Well, i actually bought a dozen out of curiosity. I haven't even opened them, they say you need a hammer to open these scary thing.

I swear, i freaked out when i saw these voodoo like item. First thing that went to my mind "are they little bats?" i then looked closer, it looked like an evil head staring back at you!! lol!! then it also look like a bulls head w/ horns and all.

I didn't have the guts to touch nor pick them up, until the lady beside me told me what they were. They are called water caltrop another kind of water chestnuts. They say these are seasonal product sold especially during Moon festival .