Not sure what artillery mold is, but oxalic acid sprayed on should return the mulch to the original look.

Artillery fungus is a naturally occurring wood decaying organism, one of many that can develop with any wood mulch. There are no fungicides registered for this fungal organism but it is suggested that using spent mushroom compost in conjunction with the wood mulch (40-60 ratio) will reduce the development of the artillery fungus significantly.

It's just part of nature's cleanup crew, decomposing the wood so the planet doesn't end up miles deep in wood waste since bacteria are not so good at chewing up wood. It will go away. Alas, Nature does not always conform to our desire to have things look like a magazine cover. It could be worse, you could have a whole forest of stinkhorn fungi. :-D