I'd like to see that thingie too , mart !
Perhaps it may also have been used by a cooper/millwright/wheelwright for holding hot mild steel or iron rivets , as a transfer (from a furnace)/insulation goldbergesque item .
I can only think of a few metals/alloys that would not burn-up the wooden wagonwheel hub , when molten .... lead , pewter , tin , or (most possibly , unless the wheel-hub is totally unrelated to it's purpose) babbiting alloys .
The type of crucible that it appears to be (to my eyes , mostly hidden by the surrounding wheel-hub) would be one where a 'quick pour' would be required (long , tube-shaped) , which is why I think babbits . Could have just as well been used for pouring shot/bullets/sinkers , I suppose .