sentences: lichens can produce acid to break down rocks
docs: lichen is fungus. wheat_leaf_rust is fungus. acid_rock is rock. parmelia_lichen is lichen. lichenales is fungus_order. lichenomphalia is fungus. physcia_stellaris is lichen. group_of_lichens is naturally_occurring_tangible_substance. lichenes is division. map_lichen is lichen.