The thing in my spoon belonged to this black chicken (aka Silkie), and it was most probably some part of its stomach. Delicious, I swear! The lady at the market killed the chicken within five seconds of us pointing at it. There wasn't much blood, but it smelled pretty terrible. 30 kuai (~3 euro) for a "fresh" black chicken, talons included (they make for a good broth according to my mother), good deal I say!

Snail was a good guess, though I think I'd be more reluctant to try it for some reason.