opened a chest on a shipwreck andmy whole world changed

I opened a chest on a shipwreck and the items inside clipped and switched to colored diagonal lines, I exited the inventory and surfaced, then all the blocks around me changed to the same diagonal lined textures, so i quit and reloaded and it had changed from the immediate area to the whole world. fortunatly it was a world i started today because it has left it unable to play