The little stalls that sell various herbal concoctions and natural beauty care stuff also sell crema de caracol. This means, literally, "snail cream," and it's got a picture of a snail on it. Everyone says it works wonders on scars and stuff. But why "snail cream"? Is it made out of snails? Strange, gross, but hey, who knows. There's a snail motif in Chilean culture that crops up occasionally: Hostal Caracol, where we've stayed a few times, and a couple of galerias with "caracol" in the name, since they're winding, spiraling ramps up the inside of a building (filled exclusively with hair salons and video game parlors).
I finally asked a vendor, who was very friendly and happy to help. It's not the snails themselves: it's snail slime.