Stems and leaves of mesembryanthemum crystallinum
are covered in small protrusions (papillae). The branched stems are generally prostrate, and are angled in cross-section, while the leaves are quite thick, ovate to oblanceolate or cordate in shape, often wavy and reddish along the margins.
Flowers may be solitary or in small clusters; they are subtended by five bracts, two of which resemble the leaves. Flowers have a five-lobed calyx (the lobes unequal in length), and between 20 and 40 narrow white petals, pointed at the tip, which become pink then red as they mature. There are several dozen stamens at the center, and (usually) four styles. Plants bloom all year, most profusely in spring and summer.