This is level 59 of the Main tunnel.
All those chained crumbling tiles such as the set on Level 39 seem to have made new players apprehensive about stepping on crumbling tiles. Don't worry, these are only big patches. So you need someone fast to quickly escape the crumbling tiles. I recommend the Skater. He goes far.
- Also, there's an optical illusion on some 'Snake' levels(e.g. Level 20). See the crumbling tiles in the distance of the photo? The crumbling tiles seem to bend inward, but they don't.