cooked crayfish!?

[splitadams]

so this morning i feed my milk-spotted puffer a crayfish after a few hours i notice that he is passing what looks like parts of the crayfish' shell, but its red, as if it was a cooked, is this normal? i thought maybe that the stomach acids of the puffer may have "cooked" the shell of the cray he ate before passing it, ontop of that lately ive noticed him passing large peices of snail shell aswell, and during he seems to be in alot of discomfort, darting around the tank like he's frightened of me, which isnt usually the case since hes happy enought to eat from my hand and when im moving tank ornaments he swims between my fingers playfully, also the colour of him fades to a light brown with his patterns dulled, but when he's finnished doing his thing, his colour returns and he's straight back to attacking his reflection as usuall

[Idontknow]

Some shellfish turn color when they die. I am not sure about crayfish though. I know ghost shrimp turn orange when they die. So do some crabs.

[edmlfc1]

Not sure about how it affects them when they pooh. But Elvis darts around the tank also when he pooh's. They eat these things in the wild so it's a natrual food for them. Sorry I'm not much help on this subject.