#1405: Meteor

XKCD comic, described below.
Transcript

[[Person A approaches Person B with a rock in his hand.]] A: Check it out - I got a piece of a meteor! B: Actually , it's only called that while falling. Once it lands, it's called magma . My Hobby: mixing pedantic terms

No, only LAVA is called 'magma' while underground. Any other object underground is called 'lava'.

ExplainOriginal