Yesterday when working on my tank, I saw some weird behaviour I have never seen before "“ all the brittle stars in my tank (dozens and dozens of them) started to wave their tentacles in the water (while the lights are still on). Looked like Aiptasia at first, but on closer inspection, their body was hiding from the light, but tentacles out. Anyone seen this before? Is this a sign of anything? Were they trying to catch something in the water stream? I probably loosened the substrate in the fuge, so maybe they could smell something?