The Common Houseleek

When we moved here, in 1987, our friend Börje, a keen gardener, arrived with a lot of plants which he placed out in our garden. One of those plants was this common houseleek which he shoved into a small crack between these two pieces of bedrock. It seemed a cruel place to leave a plant but it survived in this world of minimal soil. 
After 30 years the rosettes had increased and spread. Then it suddenly flowered one year and this year it's flowering again, for the third time I think. The flower, pictured in the extra, is very complex on its miniature scale.
The common houseleek, Sempervivum tectorum, is a slow developer, but certainly seems a tough character!