Thats exactly what happened with my sunset monti. Actually it fell behind some live rock and to be honest I forgot it fell. About a month later I was rearranging my tank and I found the tile underneath some rock and it was completely bleached white. So I was telling Rob about it and he said don't throw it out because a lot of montis will come back and sure as s**t it's completely back two months later and thriving. It's crazy how the montis will survive.