I picked up this hitchhiker on a piece I bought at LN in Gatineau. It spreads by runners. One day the rock will be covered with little brown palm trees and then the majority disappear and the process starts again. You can see the runners that have died off as the whitish tubes on the rock.
I'm not sure, but they almost look like orange hydroid or Garveia annulata. Sliiightly different though, so it may something else.
Looks like Daisy Coral to me... Minus the whitish-greenish centers. That's how mine spreads, and it's covering a rock nicely.
http://commons.wikimedia.org/wiki/File:Knopia_octocontacanalis.jpg (http://commons.wikimedia.org/wiki/File:Knopia_octocontacanalis.jpg)