The tank is set up since nearly two months now. The shrimp have been in it for around four weeks. One small algae eating fish and one big and accidentally some small snails are living there too. But this strange alien I cannot connect with any of the other. It is around one cm in length and seems to have some kind of spine and a kind of mouth on the spiky end. I imagine some kind of flat worm. I assume it was hiding in some plant, as we bought them...
The important thing: is it dangerous for humans or the life in the aquarium?