Will GSP spread off of a tuxedo urchin?

[Tired]

I bought some GSP recently, a loose piece of mat, and put it on the sandbed temporarily while I figured out where to put it. Went to bed, and woke up to this.

My tuxedo urchin evidently found it. Yes, there is an urchin under there.

The GSP seems fairly happy, fully extended, and I feel bad taking such a good piece of camouflage away from the urchin. Will the GSP manage to spread off the urchin onto rockwork, or is it contained until/unless the urchin decides to drop it? I have a small scrap it didn't pick up, so I can put that where I like if the urchin keeps this piece.

 

[Reefering1]

I like it and would leave it. I don't think the urchin will stay still long enough for the gsp to spread to a rock. Would kill like he's growing out his hair

 

[Tired]

The GSP seems to like its spot there. I appear to have inadvertently discovered a method by which to keep GSP contained without having to trim it! I'm going to have to figure out a way to steal a snippet to put on the rock I actually wanted some on, because the urchin evidently intends on keeping its hat.
It did drop the GSP at one point, briefly. It then went and picked its hat right back up after a couple of hours. I suppose this is basically the ideal camouflage; lightweight, unlikely to snag anything, but covering enough of it to make spotting it genuinely difficult. You really have to look closely to see the actual urchin, unless it's climbing the glass or is right at eye level like this so you can see under the GSP.