This does indeed look like a whale tooth. Two species have teeth this size, sperm whale and killer whale. Although the size of the whales are very differnet the size of the teeth are similar, however, sperm whale teeth are all made of softer dentine where as killer whale teeth have a hard enamel on the point like our teeth. So if the sharp end is harder than the end with the hole in it (the root) then it is killer whale. One more thing there are thousands of fake sperm whale teeth on the market, they are made of plastic and they melt. Get a pin and heat it to red hot and try to push it into the root end of the tooth, if it goes in (and smells of melted plastic) then it is a fake.