Vermiculations (dark brown) on the cave wall (pale gray) in Frasassi, Italy. Each ropelike “labyrinth leg” of the vermiculation is about 1cm wide, for scale, and they stick out 1-2cm from the cave wall.
The patterns really stand out under UV light (bright green spots are calcite veins):
Cavers homogenized patches of vermiculations in 2006 to see if they would regenerate:
There was some regrowth as of 2010:
…and sharply defined labyrinth legs by 2016:
Here’s a nice gradient on a cave wall, where a source of sulfide gas is off to the right. The vermiculations are thicker closer to this energy source. (Forgive the weird blue edge – this is a 3D Structure-From-Motion panoramic composite image!)
Arrows point to vermiculations on cave wall:
A different, spotty sort of pattern, 105m above the water table (near a bat colony with lots of guano):