Ok, in the movie, I believe there are 2 children, a boy and a girl, that find a turtle on the beach, and I think that the boy carves a mark on the turtles shell, so the boy may be able to find the turtle later on in life. The turtle grows into a giant; reason why I don't remember. But the turtle ends up saving the childrens lives, who are adults at this point in the movie. And you can still see the mark on the top of the shell, that the boy had scratched into the shell years ago. I remember seeing this movie, and I am very curious as to what the title to this movie is. It is possible that this was a movie made for tv. It was around 1977, 1978, 1979 that I had seen this movie, so I was less than 10 at the time. It wasn't really a horror movie, but I remember the underwater shots of the giant turtle swimming through the water were tremendous and memorable, considering that this was before the aid of lame graphics.