Acro ID help and tiny little Acro hitchhiker :)

Like the title says this is a two parter. The acro i got a week ago and for the life of me i cant remember the name he told me. Got new lights too not long ago so apologies for weird colors still messing with settings. I would best describe the natural color of it as brownish purple with green bumps on it. Also The little hitchhiker i found on it a few days ago. Ive only seen it come out at night, tiny little crab of some sort. id say the size of an eraser on a pencil maybe smaller.He never leaves the acro from what i can see he just sits there. JUst curious if hes dangerous to the health of this coral or anything else in my tank.
Appreciate the help ty!!

THe acro

best pic i could get of crab on same acro as above
The acro almost looks like a bleached green slimer. The crab looks like a gorilla crab (+1) but if you can get him off and get a better ID, it may turn out to be an acro crab (Trapezia sp.) which is a symbiotic crab to certain types of acropora.
Thanks guys. When I do my water change I'll see if I can get him off the frag to get a better pic. He's just so freaking small. As for the coral under different lighting as my lights warm up to peak brightness the colors of that coral really pop at peak not so much. Alot of color has come back since I got the frag hoping it continues to do so. I actually called the guy today and he claims it's a bottle brush or bonsai acro. I'll have to Google them and see what they look like. My phone camera does nothing for the actual look of the corals color but to the eye it's brownish purple with green bumps on it.
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Yeah, I can see it being a bonsai. Those are pretty cool looking and I really hope it colours up for you.

Unfortunately, that does look like a gorilla crab and o would toss him. :(
Thanks kbuser! I'm hoping it colours up too. Still fine tuning my lights. Might need to physically lower them. Only had them for a week so hard to tell yet. Thanks for the ID too. Is there any beneficial use to a gorilla crab? Would my lfs have any use for it? To sell to someone who might want it? Or are they all evil Bastards?
If you don't wanna kill him, the sump would be a good place (though I don't think you have one, right?) Otherwise they eat clams, anemones, shrimp, starfish, etc...