I got to thinking a simple throwaway thought on this video where this dude flushes mercury in a toilet (in a closed loop)
For one thing, it's easy to think about the properties of mercury (mostly its density) but actually seeing it is really mind blowing. But the imagery of a silver fluid flowing into a toilet bowl instead of something mundane like water gave me that initial thought.
Then it stuck with me. I know it's probably unlikely that it'll be used in a similar function to blood, though given the sheer scale of the universe, you never know, but if elemental mercury were to be in a given alien's physiology, what kind of materials would their bodies be made of to allow for such dense fluid to be able to flow. And would gravity on the planet have to be lower or something?
Would it even be plausible for living creatures or would it be more likely for something artificial?
I'm not even worried about why it'd be used analogously to blood. I'm just wondering what would have to happen for it to be used in the first place.
Although for the artificial argument, there are numerous electrical applications for mercury, though I'm not sure it's for the liquid form.