It seems, a tree has fallen due to abrasion and then washed away by the current of the river when the flood. Not long after the flood receded, it seemed that someone had come to cut and pick up parts of the dead tree. But not everything is taken. A large part of the tree left for the ostreatus appeared there.
I think, these mushrooms are quite famous. Apart from growing wild, which is often sought after by fans, this mushroom is also cultivated. It is white or cream in color, looks clean and pleasant when it is in the dish. Where it grows wild, like on this dead tree, it grows in piles and overlaps. Some of them, seem to me, like a posy. It has gills that run on stems that grow sideways (pleurotus). From the shape of its fruiting body, it got the name "oyster mushroom" (Pleurotus ostreatus) in the family Pleurotaceae, because it is said to look like oysters. Frankly, I myself noticed it looked more like the vegetables we have here.
It also seemed to grow like a shelf in the dead wood. The fruit body is semicircular and the cap (cap) is slightly concave in the middle, pure white, it makes these mushrooms have an eye-catching appearance.
Further reading: Pleurotus ostreatus