They don’t look like asterinas in persons. They are much smaller, only a couple millimeters across, and they have not moved at all. My tank has also been set up for over a year and I haven’t added anything but fish in quite a long time, but they haven’t appeared till recently. I’m also not sure what the strings would’ve if they were asterinas. They are a little smaller than spirorbis worms if that helps. I will try to get better photos, but I’m using a phone camera.