What happened?!???

[Cantareadio]

He was my favorite
He was fine last night, eating and behaving normally...
I don't know if he died and they're cleaning up or if they ate him (?????)

 

[MacDracor]

Some invertebrates are extremely sensitive to environmental changes. It could have been something very small. Also possible that he was simply an adult shrimp and was getting old.
All that being said, I doubt two hermit crabs that size could take down a skunk cleaner shrimp unless it was already near death. At worst, they ended the struggle for him.
And though it looks solid in the picture, are you certain it's not a moult?

 

[Cantareadio]

I'm certain
He molted like once a month. The one on the right isnt a crab, but a snail.
He was my favorite

 

[MacDracor]

Well, if nothing else has died recently and your water parameters have been stable, then I would guess he was just an older shrimp.