A homeless man once gave me a rock. Round and smooth, from water and waves of some far of lake, it sat in my hand and seemed to fit. He told me it was "father rock" and would fend of evil spirits. He said they were all over and coming from everywhere, also there was an obscure relation to crows and birds.
He never gave a good description of what these spirits looked like, no photo, nor drawing on napkins. I'm assuming he thought I would know when I saw one, and simply left that part out.
So far I've thrown Father Rock at six people,
their spirits seemed evil enough at the time.