An amazing photo. It's not something I've seen before. It's a little unclear as to the form of the fungus. It just looks like blisters, but was it lumps, cups or immature brackets? Is it possible for you to be able to revisit the site and check if it changes over time? As terrible as the fires are it is also an opportunity to gather some important information about fire responsive fungi. I know a mycologist in WA who has had done a great deal of work on fungi and one in SA that I will be able to run 'unknowns' past if you are willing for me to share your image.
PS if you're able to get back and it's at all possible would you be able to place something near the fungus to give a scale, or give me a rough idea of the size of the lumps please Marg. My thoughts are with everyone on the South Coast during these terrible times with the fires.