What might these be?

[o.c.d.]

Dictyota, I'd pull it now when its small, you'll probably always be yanking it from the same spot unless you can pull the rock and chisel off the part of the rock where it's growing from. It does look cool but not many thing will eat it to control. The only place I would let it grow is in a refugium. Diadema Urchin is suppose to eat it, I wouldn't buy one unless you find the stuff popping up everywhere.
The Neomeris I wouldn't worry about. Usually it only thrives during the break in periods of new tanks.