Schlechteranthus albiflorus unusual leaf-pairs

The leaf succulent, Schlechteranthus albiflorus, has a distinctive leaf shape. Each leaf-pair is joined at the base, forming a column below as new pairs are added at the top of a stem. A pair splits halfway up the leaf length into two chubby, spreading upper halves that face up. Fine lines form the smooth margins of the upper surfaces and the keel behind. Small mucros protrude at leaf-tips (Smith, et al, 1998; Herre, 1971; iNaturalist).