Melocactus matanzanus

I bought this cactus a few years ago at a local nursery when is was very small, did not know which cactus it was. This year, it suddenly develop a very strange wooly centre. I was a bit worried and after some research on the internet, i saw it is a Melocactus m - with maturity it develops this strange centre. The flowers are beautiful, very very small.
Regards, Mercia