Anemonie Crab question

[MrManz1691]

I have what i was tol dis a anemonie crab. However he doenst live in any anemonies. He has two or three anemonies living in and on his shell. He has crazy long skinny legs, one big claw and one small claw. He is awesome. He jamms across the sand at night. He largest tail anemonie is pink and grey. Are these guys bad for a reef? I just got 4 large feather dusters and dont really want to wake up one mroning to see them all cut up. Is this a good crab or a bad crab?