Reference: Royal Society of Chemistry
Sulfur dioxide is a colorless gas with a suffocating, choking odor. It is toxic to humans and concentrations as low as 8 ppm will produce coughing. Incredibly, in the Odyssey, Homer describes the burning of sulfur (formation of SO2) as a way that homes were 'fumigated'.
Diamonds and graphite, the "lead" in pencils, are both made entirely of carbon. The only difference is how their atoms are arranged.
Prairie dogs, those little pups popping in and out of holes on vacant lots and rural rangeland, are talking up a storm. They have different "words" for tall human in yellow shirt, short human in green shirt, coyote, deer, red-tailed hawk and many other creatures.