I beleive they call it the mulberry comb and breeders at least of australorps to be careful of it.
We bred 4 hens to our rooster this last spring collected 4 eggs from each hen marked the eggs one hen produced three of these mulberry combs.. Im waiting to hear from a breeder as what to do? Just retire them to egg layers pen? This is a new flock for us , so Ive seen bits of it befor but dissappeared around a year, not a solid black comb.
Would be interesting to see what an expert has to say about it.
I will see if I can find the article about mulberry combs on these birds, not a good think I suppose, over all, all three hens are very well built birds, combs nice and straight nice points but just wrong color.
Out of those 4 eggs 3 hens one rooster all three had this, not a nice comb on the rooster twisted front . the other hens didnt produce this color variation.
If I find the article, I will post it in here