In Kingdom Come Deliverance 2 there is a quest where you have to banish some demons from a castle. During the quest one of the cooks asks Henry what the demons look like and one of the options is black sticky tar.
I always choose that one so that canonically Armus is in 15th century Bohemia.
Fun fact. La Brea means "The Tar" in english. So we basically call them "The tar tar pits".