The invader taking Toenail’s children has a real name, and it may be living on a foot near you right now.

Onychomycosis is fungal infection of the nail, one of the most common infections in the world, affecting perhaps one person in ten, and many more with age. The usual culprit is exactly the one Wollumbin names: Trichophyton rubrum, a fungus that has evolved to do one thing supremely well, eat keratin, the very protein the Keratinocytes give their lives to build. It digests armour.

The invasion usually begins precisely where the story says the wall fell: at the distal edge of the nail, the Distal Groove, where the plate meets the world. From that one foothold the fungus spreads slowly back toward the Matrix, and the once-smooth plate turns thick, ridged, yellow-grey and crumbling. It advances at the speed of a growing nail, which is to say patiently, over months and years, a siege, not a blitz. That slowness is why it so often goes unfought: each week looks almost like the last, and a people can learn to call decline normal.

And Wollumbin’s harder teaching, that something within opened the door, is honest medicine. Fungi feast where sugar is plentiful and defences are distracted: onychomycosis is far more common, and far more stubborn, where circulation is poor and blood sugar runs high. The sweetened blood she tastes in the capillaries and the sickness on the surface are one story, told at two depths.

Meet the Dreaded Onychomycosis in Chapter Four · Go deeper: Keratinocytes & the nail · Enough