They will step on them and everything, but won't attack a perfectly fine one. I've seen an amano rip apart a shrimp having a harder time molting. I doubt it would have died if the amanos weren't there, but I'm still not taking them out as the algae they eat is crazy!
ive seen Rilis tear apart a crystal with the victor devouring its prey with legs still twitching. Shrimp are opportunistic bottom feeders. Don't assume just because they are peaceful that they wont be hungry...
Never seen my Amanos evenlook at any of my shrimplets. And they say ghost shrimp will eat shrimplets but I have never seen them bothering shrimplets. The shrimplets are to fast and ghost shrimp eventhough they have little claws, there weak and again to slow for healthy shrimplets.
I agree that the shrimplet was either dead or dying. Amanos are pigs, but they're not predatory. The amano probably just beat the other CRS to the body, or it snatched it from the CRS and made off with it.