I'm not sure what this is, but an image search suggests it might be a stonecrop of some sort. Maybe a white diamond stonecrop? For those of you who want to take a guess, it's about two feet across and was growing out of a vertical face (mostly just dirt, though, not stone).
Clearly intended to attract the eye of the unwary.
Or make a Vulcan go hippy...
https://youtu.be/SfdRVtIyFQc
If it is a wild (rather than cultivated) plant, it is probably in the genus Dudleya, which is in the stonecrop family. There are many, mostly coastal species in California and Baja California, but they can be difficult to identify.
The flower as I know it is Hens and Chicks - I don't know if correct but my mother had several growing out of some rocks in Kansas. They were super hardy and survived the winter in Kansas. There are probably different types
https://www.gardeningknowhow.com/ornamental/cacti-succulents/hens-chicks/growing-hens-and-chicks.htm
It is beautiful, and well shot, but saying "stonecrop" doesn't seem to narrow it down much. There are 400 to 500 species. ADM's suggestion seems likely:
https://en.wikipedia.org/wiki/Dudleya#/media/File:J20180111-0014%E2%80%94Dudleya_farinosa%E2%80%94RPBG%E2%80%94DxO_(25841707838).jpg
where was this photographed? Very cool!