The tunicates died back about two weeks ago. We thought we had perhaps poisoned them with the algae concentrate we had been using, but now it looks like they are growing back. Perhaps a natural life cycle? We'll see what happens this time. We discovered at least two other species of tunicate in the tank that apparently hitched in on the live rock. No idea on the identifications, but we'll see what we can find. It seems like every time I look into the tunicate tank, there is something new popping up. Very exciting!