bone, body, corpse
骸 centers on the physical remains of a living thing after death: the bones, the body, or a corpse. The idea connects the structural framework (bone) with the whole dead body.
骸 combines 骨 (bone) with 亥, which likely contributes the sound. The character originally referred to bones or skeletal remains, extending to the whole corpse.
The left side is 骨 (bone), and the right side 亥 looks like a twisted body. Picture a skeleton with its bones jumbled together — that's a corpse.
For ガイ, imagine a guy discovering a skeleton: guy -> ガイ, and the bones are all that remain of the body.
ruins; wreckage; wreck; broken remains; debris
(dead) body; corpse; carcass; remains
skeleton
(soulless) body
remains; corpse; (dead) body
remains; corpse; body
becoming a mere shell; becoming a dead letter; losing (one's) substance; being reduced to a formality
holy shroud (i.e. the Shroud of Turin)
supernova remnant; SNR
hopper crystal; skeleton crystal
coke (carbon fuel)
to tender one's resignation