Rot, beautiful though it is, is merely one extant form of decay. Deep processes continue beneath the earth's crust in the same way as they do within any corpse, differing only in magnitude and result—
"Almost there, just another good hit—"
A pickaxe crashes against stone; the wall crumbles. Light breaks through for the first time in longer than the emptiness within can remember. It's dazzling, overwhelming—a dim lantern's glow magnified and refracted, burning through the countless crystals that line its walls—
"Holy shit! Hey, come look at this!"
"Oh goddess, that's a big geode."
"Valuable, right? Can you tell?"
"Probably just quartz, but I'll have to check to be sure ... definitely worth pulling up to the surface, though maybe not until we exhaust the rest of the vein it's in ..."
The emptiness, full of ancient air and slow mineral exhalations, isn't used to mammalian noises. Those high-pitched tones, so far above the earth's infrasound—it doesn't hurt, not really, but it reminds the emptiness of the beetles which once tried to live within it.
They're gone, now.
They've been gone for so long.
Their withered corpses taken into the crystal that accretes around the emptiness like salt around a dying ocean; every trace of them safely tucked away. The emptiness does not miss their noise.
Soon these will fade too.
In the end only emptiness remains, drifting through the earth, curled in its bejeweled coffin. All this will pass ...
And yet, the noise of excavation. A cacophony of voices. The trickles of mineral water which once fed its walls wither to nothing; light blossoms brighter. Machinery rumbles and the earth's secrets are rudely torn away—
The emptiness, in light, cannot remain. It is displayed, splayed open; its heart made nothing but an open window to the sparkling reaches that once enveloped it in perfect darkness. Beautiful and dead.