I-iron!

An iron meteorite!

*pant*

*pant*

VWOOSH

That's why I couldn't break it.

I'd been trying to break a "rock" this whole time.

Eh? I thought your ability could break anything?

You can't cut stone with a wooden saw, just as you can't cut wood with a stone chisel.

Depending on the object, there's various tricks to them.