Maybe Clathrus ruber.

I think that it more closely resembles Clathrus columnatus, which is just one of the many fungal organisms commonly called stinkhorn mushrooms.

Because they smell so horrible, I would remove and dispose of them, even though they are not the least bit harmful. Some reports state that these are even edible!

Stinkhorns feed on organic debris in the soil or on the surface....like mulch.

most likely.. its growing in the rotting mulch below the surface ...

i consider mushrooms and the like.. as a free show from mother earth .. and revel in them.. rather than remove them .. most are so ephemeral .. last only a few days that it isnt all that big a problem ...

key word.. free plant ... lol ... yes i know.. its not a plant .... you get the point

ken

Ken, that's a nice and valid thought, but have you ever been in close proximity to a ripe (mature) stinkhorn? Think eau de rotting carcass!

OP, whatever your friend thinks of them, it is absolutely not something than can be sprayed or treated with chemicals. Chop out the mushroom with a shovel to dispose of it, or just let it be.