Is there some substance that X. The answer is always yes, because he universe is a huuuuuge place. That you fact that you haven't heard of X means precisely zer

Is there some substance that X. The answer is always yes, because he universe is a huuuuuge place. That you fact that you haven't heard of X means precisely zero unless this is your expertise. Dymethylmercury immediately that pops into my mind https://en.m.wikipedia.org/wiki/Dimethylmercury https://en.m.wikipedia.org/wiki/Dimethylmercury