Since 2014, a Danish artist by the name of Thomas Dambo has erected dozens of wooden, folklore-inspired trolls in greens-aces and parks around the world: a seated, bearded dude in Copenhagen’s hippie enclave of Christiana; sister and brother trolls “lost” in Florida’s Pinecrest Gardens; a series of wooden giants (one playing the flute) outside of Seoul, South Korea.

They’re certainly a sight to behold, but the best part is that they all utilize scrap materials from wherever they’re built: plywood that protected buildings from a hurricane becomes an “island guardian” in Culebra, Puerto Rico; fallen branches and twigs morph into spikey troll hairdos in Denmark. “I want people to know that trash has value,” says Dambo. “And the trolls do that, and also help me tell stories, like the legends I grew up with.”

For anyone who lives in, or visits, Scandinavia, trolls are everywhere and nowhere, hidden in the woods and writ large in the region’s literature and tourism. Long before trolls got turned into eco-warriors by Dambo (or candy-colored cartoons in Trolls World Tour), they showed up in old Norse mythology and poetry as far back as 12th-century Iceland.

Trolls had dual lessons to teach humankind: first, that the unknown world beyond the village or castle walls could be uncertain and potentially threatening; and second, that the risk of such exploration might yield knowledge and riches.