“ Mining in a certain area turns all exposed skin (maybe just parts that are actively disturbing the chemicals that cause the reaction) of the those doing the mining to a dark blue color. Will wear off taking as many years/days spent in the mine.”
“ A weapon of war created by an extinct race, this rat appears normal but is a simulacrum - beneath it's mangy fur is a body of bronze. Commanded by words in a lost language, wherever it goes a virulent and lethal plague follows. The cure is similarly obscure.”