I've got odd finger and hand pores that seem to collect 'matter'. I have one on the side of my hand and then one big one between the knuckle and main finger joint on most fingers. Every so often I will peer at them and there'll be a delightful little shiny black head in there and what emerges is a squiggly worm of beauty. Saw one glinting tonight in the fading sun (not in UK!) and here's the result or a bit of a squeeze.
I BET if you look hard enough you'll have some too. I love to leave them to bake for a while ... imagine whiling away the hours on public transport with your own handy stock of sporn wonder.