I've not heard of the laser before, but I'd use a harlequin. I have a 75 g, and it was loaded with asterina. I put in my harlequin, and he destroyed them. It took some time, as he'll probably only eat one or two a day, but he absolutely wiped them out. As for the chocolate chip star, I have 5 four legged ones in my sump, and actually, one's down to three legs. They can't grow them fast enough for me to cut them off. I probably am going to get two more, as I feel like I'm farming them... I know you said that all he did was hide, but mine is funny. Once I started feeding him the chocolate chip star legs, he's actually pretty active, and I can tell when he's hungry. He'll be in a cave, and I'll toss in a leg. It's like he can smell it. Within minutes, he's all over the place looking for it, and always has it within a few minutes. When ever he's out and about in the front of the tank and not hiding, I know he's hungry. He just grabs the leg and hauls it back into a cave with him and munches on it til it's gone. Have patience on the shrimp, he'll deliver for you.
