I saw it's silhouette for only a few seconds. It was about three inches long and had distinct tentacles of some sort coming from its head. Apparently it saw us, as it quickly slipped into an opening in one of the corals and disappeared. I haven't seen that before. I'll bet that's our fish killer.
Predators are part of an ecosystem.
The bell rang, and we both rushed off to our respective classes. The terrorist is still in the tank, and last time we looked, there were still five of the Damsels and the Blenny swimming around. Certainly, the existence of the shrimp will keep us from putting any expensive species in the tank. It will probably also mean that we will lose many of the fish currently in there. It would not be difficult to remove the shrimp.