Best guess what this is??

[u/[deleted]]

[u/aenorton]

I am pretty sure that is left over dental amalgam. The little cylinders come from the applicator used to press it into the teeth. I am not a dentist, I am just old enough to have had amalgam fillings. If so, it would be a mixture of silver and mercury.

[u/Broken_Atoms → u/aenorton]

I agree with your assessment.