Unidentified "fairy mushroom"-type fungal growth below bathroom skirting

[gabadab]

This fungus was growing between a bathroom skirting(painted) and the tiled floor. The room is moderately heated.





Although in the past I have found bright blue copper-staining on a secluded area of floor- tiles, indicating a plumbing problem, I was surprised to find a 8"x 4" patch of quite dense, greasy, black, sooty deposit of spores in the same area. Having tried, with difficulty, to wipe it up with tissue, I realised that it also contained the collapsed, dried remains of seemed like what I used to call "fairy mushrooms". By now the debris was crushed, but seemed to consist of a very fine stalk 3-4cm long, and a lighter cap, perhaps with black gills underneath, though these might have darkened with decay.

I know enough about dry rot to think this is something else- less destructive, hopefully - but can anyone suggest what it is & how worried I should be? Clearly I also need to have the plumbing checked!

I can send images, whole and section, of the only remaining immature (unopened) cap, about 1cm, a whitish/fawn, rounded conical shape, removed before a stalk had developed, but they are not very clear.


Hope someone can help, please?