One of my sps frags got dinged-up in the recent house move, and during its sojourn waiting for the tank to cycle, developed tufts of hair algae on its battered growth tips. The frag, about palm-sized, has started a recovery and has good polyp extension everywhere but those poor tufted ends.
So one of my scarlets found his way into that delicate structure of closely-grown acro tips and is doing, every night, what human fingers couldn't---delicately picking off that algae and cleaning the tips. I'd have had to break every one of them off, and risk damaging the still-fragile frag in its recovery---but thanks to the habits of scarlet hermits, the frag is getting picked over by claws the size of a dental pick and there's no further damage to the frag where the scarlet is resting by day.
This particular species of crab never gets bigger than a pinky-nail, and is particularly good at acro-batics, getting in where humans can't, and keeping the algae off. If they occasionally park there to molt, no big deal: the coral tolerates it.
I'll never have a tank without these attitudinal little jewels.
So one of my scarlets found his way into that delicate structure of closely-grown acro tips and is doing, every night, what human fingers couldn't---delicately picking off that algae and cleaning the tips. I'd have had to break every one of them off, and risk damaging the still-fragile frag in its recovery---but thanks to the habits of scarlet hermits, the frag is getting picked over by claws the size of a dental pick and there's no further damage to the frag where the scarlet is resting by day.
This particular species of crab never gets bigger than a pinky-nail, and is particularly good at acro-batics, getting in where humans can't, and keeping the algae off. If they occasionally park there to molt, no big deal: the coral tolerates it.
I'll never have a tank without these attitudinal little jewels.
yes i too also believe that hermits are a very important part of our worlds 
