Those are sponges. First pic kinda looks like pineapple sponges. Google them and compare to what you have.
second pic looks like a sponge I cannot remember the name. If they are white and kinda stringy looking with new runs branching out, then they are what I am thinking of.
Both are harmless and will self regulate with their population. The white stringy ones can annoy things by touching them, but they don’t actually hurt anything.