I have also seen them from chewing on parsley and lemon.
The fact that there was no oil to contract the gallbladder is even more proof that these were not gallstones, but rather a cholesterol-sterol complex. Parsley contains sterols that bind with the cholesterol secreted in the bile forming cholesterol-sterol complexes in the intestines that people mistake for gallstones. The reason sterols are used to lower cholesterol is because of their strong affinity for cholesterol.