The saltiness of the sea comes from dissolved minerals, especially sodium, chlorine, sulfur, calcium, magnesium, and potassium, says Galen McKinley, a UW-Madison professor of atmospheric and oceanic sciences.
Today’s ocean salt has ancient origins. As the earth formed, gases spewing from its interior released salt ions that reached the ocean via rainfall or land runoff.
Now, the [...]

Built for crunching and chewing, teeth mostly consist of hard, inorganic minerals like calcium. But they also contain nerves, blood vessels and specialized cells that manufacture the tooth’s different parts, says Bill Gengler, a veterinary dentist and oral surgeon with the UW-Madison School of Veterinary Medicine.
The tooth’s outermost layer – the part we brush – [...]