If the cake had brown crust I would have mistaken those for shiitake pins. If those are infected with Wet bubble (mycogone) it may be difficult to get you area clean again. CattyMcBats has some stories and threads about how long it took him to get from from it.
Well sort of. My thread on the subject is posted above on the thread already. In that particular case, I was mistaken, it was just how the oysters pinned.
I have however spotted mycogone perniciosa on a colony or two in my day but luckily caught it in time. The problem with it is that it is extremely prolific in spreading its spores and they can lay dormant for about a year, not only that, but they have two different spore types, one being hardier than the other. Keep in mind, all of that info is from memory, so forgive me if I made a mistake.
Edited by CatsAndBats, 13 November 2019 - 08:48 PM.