Everyone should have one.  We are obsessed with fossils and T Rex teeth don't come along every day, especially at anything like an affordable price.  We have not had the tooth certified but bought it from a reliable source and are happy to take it to the Natural History Museum for more details if you would like.  You probably know about their identification department anyway if you are interested in sort of thing - they are brilliant and can't wait to share their enormous knowledge - fantastic for children and adults.  This tooth is around 100 million years old from CARCHARODONTOSAURUS SAHARICUS and is 40mm x 20mm