Scientists have been studying a fish that can breathe air and 'walk' on land to find out more about evolution.
It's thought that all life on Earth started in the sea but about 400 million years ago fish began to go on to the land and eventually changed into tetrapods: animals with four limbs.
Over time they evolved into the amphibians, reptiles, birds and mammals around today.
Researchers at McGill University in Canada have been looking into how early fish made this move to land by studying a living fish, called Polypterus, which can 'walk' using its front fins.
Have a look at the slow motion video of the fish in the lab showing how it 'walks'.
Video courtesy E.M. Standen and T.Y. Du, H. Larsson