Sedum sexangulare is as the name suggests; six sided. The foliage twists in a spiral up the tiny stems in a very pretty texture.
Although low growing, it can hold it's own against taller types and species. This isn't to say that it is aggressive, just assertive in its growth.
In time, it forms a beautiful flowering groundcover - in the picture above, that started with one plant, spreading over the span of two or three seasons to cover around three feet square, or one square meter.
The effect of the frilly foliage topped with the bright yellow flowers that open in July is so pretty. Even if it's not blooming, the bright green of the leaves covers the ground entirely - this is no sparse and balding type of ground cover. I've never pruned this plant - if you did, it would make it even thicker.
I also like the contrasting textures in a Sedum tapestry, or draping over the edges of a container.