Might anyone know what this is? There were two, one on my rock and one on this shell. It doesn’t react to being touched and stayed upright when out of water. I want to think it is a macro algae but I’m not sure.
Here is an update. It’s getting bigger and has fanned out with some small fuzzy things coming out of the center. It is a bright green under white light. Also, the stem looks white like calcium.
If someone could move this to the algae forum. When I started it I thought it could be a worm. If that’s possible I would appreciate it.