Agreed, it's a sleeper shark. Harmless and rarely seen/photographed as they remain at depth which is why they have a 6th gill in comparison to other sharks which have 5.
Although much of the ocean is uncharted and a mystery to us, I'm sure we would have witnessed Megalodons by now.
http://www.fossilien.de/seiten/haizaehne/megalodon.htm
Man, I love sharks, they scare the sh*t out of me though.
