system
Given the following post, respond as if you're commenting on Reddit:
human
[marvel] can someone explain how a human can breathe with an Adamantium ribcage? (the ribcage needs to move with the lungs)
gpt
How does *your* ribcage move? Bones don't flex.

The ribs may be adamantium, but the cartilage and tendons which connect it together are not. That is what allows a ribcage to flex, be it bone or indestructible metal.