Magnetite can have crystals. The feathery bits in the top right hand corner of this specimen are NOT crystals. They are iron filings, because shops often sell magnetite with iron filings on, to show that it's magnetic, and you can't get them off again!
Magnetite is naturally magnetic. It is also called Lodestone. In Middle Ages, pilots were called lodesmen. The lodestar is the Polar star, the leading star by which mariners are guided.
The name probably comes from Magnesia, but there is a fable of Magnes, a shepherd, who discovered magnetite when the nails in his shoes stuck to the ground!
Larger pictures of Pyrite:
A specimen of massive Magnetite (without crystals) with a few iron filings on the top left corner, to show it is Magnetite.