Last week I noticed a seed pod split open on my Astrophytum Ornatum - the seeds are hybrid, but I collected them, dried them on a kitchen towel for a few days, cleaned off the pod fibres, and decided to sow them.  They might make some nice gift plants - Mrs C is always after any spare cacti I might have - to give away.  There are about 200 seeds, and I have no idea what the other parent is at present.  So I sterilised a mix of loam and sand, and sprinkled 100 of the seeds on top, covering them with bird grit.  This was Monday evening.  
This morning (Wednesday), just 36 hours after sowing, a handful had actually germinated - I couldn´t believe it - and certainly a record for me in 57 years of growing.  Currently, Wednesday evening -about a dozen are up !!!  I am gobsmacked with the speed of this !!