I have nine in my 37 gallon they were pretty small when I got them but have been growing slowly. they havent been any problem with my leather shrooms or polyups.
they tend to hide during the day in holes in the live rock and come out as the lights are cycling down
I bought a few when i set up my first tank. I am three tanks into it and they are still with me in a 90 gallon. They have coraline algae growing on them now so it is hard to tell they are bumble bees. I like them because they can get into places turbos and astrea cannot due to size. They are hardy and good eaters for their size, and I have never seen them bother a coral.
I have a bunch of them in my tank and they seem to be one of the better scavengers. They're carniverous and eat any scraps that the hermits and shrimp leave behind. Mine too are covered in coraline so they don't have the bumble bee look anymore. Never saw them bother any corals either.