On a recent visit to the San Francisco area, a friend introduced me to the playful world of “Yarn Bombing.” Also known as “graffiti knitting” and “yarn storming,” this public knit-art trend is popping up all over Berkeley. Working under the dark of night, the city’s knit bombers’ campaign creates unexpected yarn sleeves for public works of art, traffic signs and more, to many Berkeley citizens’ glee.

The stormers themselves remain anonymous, though one pair going by the name StreetColor has been labeling its installations, and has even started its own blog to document work. Another, the international organization called KnittaPlease, may be serving as inspiration for some of the work as well.

Take a look at a handful of yarn bombs below. They’re excellent reminders that the world is full of beautiful surprises; you just have to keep your eyes open and pay attention.

*Image by StreetColor’s “Russian”

*Bottom photograph from StreetColor. All other photos by Anna Carnick.