Where was it found? What minerals was it found by? And can you get a clearer picture without the glare? If we can't help you out check thefossilforum.com.
And my opinion is it is not a shark tooth due to the lack of serrations. It doesn't appear to be a mammal tooth or a dinosaur tooth. I think it is some sort of concretion or something to do with mineralization (those horizontal lines)
It looks like there is a build up of calcium carbonate, and it looks like there might be a sharks tooth under the matrix. You might want to have cleaned. You can use some diluted Muratic acid and slowly clean it. But it does resemble a sharks tooth.