Mercury is the only naturally liquid metal on the planet, and you've got to admit liquid metal is pretty awesome. It's also classified as a "heavy metal". Also awesome. But despite all its awesomeness, Mercury is still a neurotoxin that has been linked to immune system suppression and a host of physical problems including brain damage, Autism, Alzheimers, ALS, MS, Cancer, and other chronic diseases. What may surprise you the most is how much mercury you're exposed to without even knowing it.