Sedum lineare also known as carpet sedum, needle stonecrop or sea urchin, is a sedum originating in East Asia.

It has been proposed as an ideal plant for the “greening” of flat-roofed buildings in Shanghai, China, due to factors such as its ability to tolerate cold and drought, little need for soil and its roots’ lack of penetrating ability.

Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Core eudicots
Order: Saxifragales
Family: Crassulaceae
Genus: Sedum
Species: S. lineare

Hardiness zones: 7-11.
As with most sedums, this is drought-tolerant. I rescued this one from the usual saturation in a garden centre.