Judging from your picture, this is a jumping bug.

Jumping insects are non-insect hexapods of collembola, which look like soot, also called soot insects. Jumping insects mostly occur on culture materials, often concentrated on the surface of mushroom bed or in dark and humid places, biting the fruiting body of yuanmo, causing pores, carrying and spreading miscellaneous bacteria. This kind of worm reproduces quickly.