40d:Glowing pits

This article contains massive spoilers. If you do not wish to have your game experience spoiled, do not scroll down!

If you dig deep enough in the right (or wrong) place, perhaps following that vein of glorious adamantine, you might break into a peculiar chamber with strange glowing pits at the bottom.

There will frequently be chained and caged humanoids, bones, meat, chunks, body parts, and bones ground to meal of said humanoids, upright spears and pikes, ash and charcoal, and horrifying engravings. These are a warning. If you do not take drastic measures such as rewalling the chamber to seal it, the glowing pits will unleash a demonic horde upon your fortress.

Pits contain a very small amount of magma (usually enough for a handful of smelters or forges, but sometimes multiple small deposits enough for a good-sized industry). This is fortunate, since magma is a requirement for adamantine refining. But you'll have to deal with the demons first...