Mystery Hitchhiker/Inhabitant

[NySharkBait]

I was feeding my fish when I noticed a pair of antenna sticking up from my rock work. They're moving with purpose, so it's not a molt from my Skunk cleaner. I can't see what they're attached to. Any ideas on hitchhikers with antennas? They were approx 2" long, so fairly decent size for something I've never seen. 29 BioCube.

 

[SNAKEMANVET]

Need a pic to help identify.

 

[frey]

pic would help, but sure its antennae and not just a pair of legs from a brittle star?