I thought of how something like this could happen. I imagined the fish swallowing an egg. Then the thing grew inside of the fish and finally grew big enough to emerge violently out of the fish. I'm still not sure what it is. Probably some kind of turtle without the shell, using the fish as the shell.
I am part of a 3d modeling company called 3d Aura Studios. Here we aim to create quality 3d models. If you have something you wish to be modeled for you, we would happily take on that job no matter what your budget is or how difficult or easy you think the project will be. It doesn't matter, we will do our best. If our best isn't good enough, we'll do even better!