The black things in your hot and sour soup are called wood ear fungus which is healthy for you and safe to eat.
The wood ear fungus is basically just a type of mushroom that Chinese put into hot and sour soup.
It can seem disgusting for the black things to be in the hot and sour soup but they are actually pretty good to eat and are beneficial for your health.
If you do not want to eat the wood ear fungus mushrooms in your hot and sour soup you can just remove them or just eat the rest of the soup and leave the wood ear fungus or those black things in the soup.
I eat the black things which are wood ear fungus or basically just mushrooms and they are pretty good to eat and hot and sour soup is delicious and also good for when you have a cold or flu.