It wasn't the most powerful shark I have seen. The first shark I met had an attack of 50, but a max hit points of only like 200. Of course, it never made it that far in regaining hits. The latest sighting had a 40 attack, but max hits of over 900! Of course, it too did not live long enough to heal any real hits before my dread tanked it. All in all, sharks are pretty darn rare alright. And they do seem to tailor themselves somewhat in attack and hits to what people are able to fight it with. The problems: A shark too early is unkillable by anything less than waves of frigates or battlehammers. If you don't have those kind of ships yet, time to play dodgeball with it. A shark too late starts with so few current hit points that the first battleship or dread that rides up kills it. The ultimate shark would balance the attack rating to what people can throw at it, and have variable max hit points, but would start fully healed instead of weak.