Méret Oppenheim is ranked among Switzerland’s most well-known artists, known for her vast surrealist oeuvre, and most iconically, for her hairy 1936 work Le Déjeuner en Fourrure (Luncheon in Fur). One of the last masterpieces Oppenheim ever created is considerably more obscure but no less strange than the famous furry teacup, and it can be found in the heart of her chosen home city of Bern.

Spirale (Gang de Natur), or The Spiral Column (Nature’s Way), is a spiral-shaped column made of concrete and aluminum. It rises several feet high, and functions as a fountain with water running down the outside. But what makes this piece so unusual is that over the years, the once plain, brutalist-style column has changed drastically in shape and texture. Water and minerals have created bizarre chunks of tufa, a kind of limestone, that “grow” on top of the object, as well as several kinds of plants, mosses, and lichens.

What’s more, the piece changes its look every season. When frozen in winter, the fountain is covered over and over with icicles. In spring, tiny flowers bloom on top of it. Indeed the sculpture at Waisenhausplatz in central Bern has grown so fast that in 2013 it required radical renovations. Some 880 pounds of material was removed in order to maintain the object’s stability. This coincided with Oppenheim’s 100th birthday, and since then the lumpy, organic shape has grown back.

Meanwhile, Bernese inhabitants are not aligned in their opinion of the obscure fountain. Some complain about its sheer ugliness and costly maintenance, while some admire its ability to transform. Whereas biologists appreciate the unique biotope that has been created in the middle of the city, others complain about the moldy and rusty look. Since Oppenheim herself died two years after the fountain’s installation in 1985, nobody can even be sure about whether she intended the shape-shifting property of her work, or simply did not take into account the high chalk content of Bern’s tap water.