But there are several things that are not right for meteorite:
- it contains holes
- it has no fusion crust (these are much smoother than what you might be imagining)
- the 'regmaglypts' texture has lumps protruding (it should be ridges that protrude, as in this example)
- the overall shape is too far from equant (such a shape would break into more equant shapes in the atmosphere)
We could consider the density if you like, but I suspect it won't help much in this case, since we already know it is magnetic and it does not look like magnetite (iron has a similar density to metallic meteorites).
But if you want to check it: Because of its size, it would be difficult to measure the volume, so I'd suggest knocking a small corner off, weighing it, then using the water immersion method to determine its volume.
So if not a meteorite, what is it?
I am sure it was molten at one stage, but it does not look volcanic (though one would want to get a thin section under the microscope to make sure).
It looks industrial, to me at any rate; without lab analysis to be sure, these things are always subject to opinion. My guess would be that it is metal slag spilled in a foundry or smelter. I envisage the 'regmaglypts' being an impression of the substrate on which the liquid fell, and the smoother other side being exposed to the air hence levelled-out before it solidified (also allowing some bubbles to come to the surface). There are hints of layering, so it could have built-up in several spillage episodes.