the multiple at astonding rates to a point where you cant sount them in a few months.tweezers are a really bad idea they are like shrooms ANY little piece of it left or might float away will start a new apistia and spread even more quickly. a strong kalk past and bioling water is the best that I have used on them.
they will fight anything in the area that they want, some corals can stand there ground with them but most will only last a little while.
but yeah
1st pic hair algae
2nd apisitia ot close relative
3rd fether worm of some sort.
Mike