Worm or algae?

[swiss1939]

Been noticing a few of these dark brown squigly lines on one of my dry rocks that seems to have come from a piece of live rock i placed next to it.

Just curious if it is a worm, algae or some sort of sponge? Can't seem to find anything similar searching on here. I find all these micro organisms that grow in sw tanks to be very entertaining and am drawn to them just as much as the larger more flashy organisms like coral and fish.

Bigger one dead center of photo. Only about a quarter of inch across at most.

Smaller one dead center of photo. A few mm at most across.

 

[KJ]

Look like algea.

 

[swiss1939]

You sure it's algae? It seems to be segmented like a worm or something.

Here is another one that appears to be growing a few mm a day.

 

[swiss1939]

Bumping this as I do not believe these are algae as suggested. They are moving daily in ways that would not be possible for algae whose growth pattern once laid down would remain, and only change as it growth out. Instead, they are moving their patterns around where already laid down so what was a spiral yesterday, is a straight line today. The one circled has retracted from its footprint and moved quite a bit. So these are some sort of animal/critter. Anyone seen these before?

 

[sfin52]

Bumping this as I do not believe these are algae as suggested. They are moving daily in ways that would not be possible for algae whose growth pattern once laid down would remain, and only change as it growth out. Instead, they are moving their patterns around where already laid down so what was a spiral yesterday, is a straight line today. The one circled has retracted from its footprint and moved quite a bit. So these are some sort of animal/critter. Anyone seen these before?

Pull the rock and get a close up pic. Its really hard to say with the image provided.

 

[swiss1939]

Unfortunately it is on the base rock of my structure. Will not be pulling it for that. I may try seeing if I can get a closer photo with one of my video cameras using a telephoto lens.

I am thinking they might be some sort of brittle star infants or bristle worm infants? That rock does have the most bristle worm sightings peeking out from it. So I'm leaning towards that right now.