Some parasitic fungi

It's a fungus! Rhytisma acerinum

Autumn is almost at the end, with temperatures regularly dropping blow zero at night, but some fungal life is still in evidence. There are some "real" mushrooms on the ground, with stipe, cap, gills and everything, but the true abundance these days is found on tree leaves. It wasn't so obvious during the summer months, but it looks like all maples in the area are heavily infected with sycamore tarspot. Fortunately, it is quite harmless to the trees' long-term health, even though it looks horrible.

But at least, these fungi are feeding on plants, which is not so bad compared to the next photo:

The original of this image can be found here. It's a fungus eat fungus world out there!