Thought they were macro algae until I saw some on the glass. Ordered Flatworm Exit to treat, as well as rigid and soft airline tubing to remove. It’s quite the infestation from months of neglect on the tank. Will keep a diary of the experience here. Might remove rock and treat separately from tank to minimize die off toxicity . Quite a bit in the sand, too, though... at least it’s a small tank and a ton of water can be changed very quickly.