I've looked through my half a dozen books and so far it has drawn a blank. A feature on some fungi are to crack when they are mature- this one could well have dried. Talking about mutations, I came across a Hydnum Rufescens with a aborted cap on top of its cap!

Mark

It certainly looked cracked, like the inner meat was shyly exposed, and almost vulnerable!

Mushroom mutations are opening up a whole new world for this fungiphile...what a trip!