After stumbling into a cave in Celestia-knows-where, Fluttershy finds herself stepping in a puddle of green goo not unlike the fluid found in the cocoons changelings are known to have used to store their prisoners. Suddenly, her hoof turns to chitin and the flesh around it begins peeling away, revealing more hole-riddled chitin underneath. While painless, it is nontheless alarming for the little pony. FA source