The odds for a flowering plant may be unfavourable, yet that doesnt necessarily mean impossible! Life is tough, but the living are sometimes resilient. A seed may land on stones and fall through the cracks until it reaches some soil below. Or maybe it did see the sun way back as a young plant and became covered by quartzite through a mishap involving something like an unaware or careless passerby.
Whatever happened here, this mesemb managed flowers, and several of them! It may be a Conophytum, a Lithops or some other Aizoaceae genus with long, erect flower tubes. If the flower tube had been short, also the flowers would be invisible, covered by the pebbles.
Now one could speculate about the likely fortune of the seeds that will follow…