Originally Posted by
sktarq
I assume you are talking about the mercury.
Mostly I came up with that for a few reasons...
One mercury was a display of wealth material like gold or ivory for a long time. Aztec, Egyptian, and Chinese tombs all have been found with the stuff as a status marker. It has even been used as "water" in large models of palaces etc (where I got the idea) and is thought to have been used as a bed in another case. And this is by humans, another apex predator.
The idea of it being a concentratable toxin is rather new view of mercury.