mammillaria backebergiana - Seed pod/fruit

Hi,

I've just noticed a seed pod/fruit on my mammillaria backebergiana.

What should I do to collect the seed the seed to grow on? I've assumed its not ripe yet so left it alone.

It's quite exciting as this is the first time any of my cacti have produced a seed pod/fruit and I'm looking forward to growing a 2nd generation plant from one of my own stock.

The books say that the fruit is dull green, but becomes purplish-red when mature. So if it gets reddish then I would see if I could easily detach it, but if not just leave a little longer. If it seems to be drying up, then the seeds certainly would be ready. Don't rush it, as seeds need to become ripe to germinate well.
Good luck with it.