Description: This is a miniature cactus that  makes a nice and tangled cluster of fine crests.  The stem surface is completely obscured by small pectinated  ashy-grey to white spines.
Tubercles: Numerous, not confluent into ribs, hemispheric or short cylindric, very small, ca. 1-3 mm; arranged in tight spirals around the plant.
Areoles : Small at tips of tubercles, 1 mm long, nearly circular, elliptic when distended by flower or fruit, slightly woolly when young, copiously woolly only at sexually mature stem apex; areolar glands absent;
Spines: 20-35(-40) white to ashy grey 2-5 mm long, appressed on sides of stems, straight,  innocuous, in 1-3 superimposed series except for a longer (4-12 mm) and erect adaxial tuft on the top, on sexually mature stem apex often greyish or purplish white, frequently with brown bases, collectively forming brown spots at the centre of each spine cluster.
Roots: Diffuse (usually) or tap-root (in some populations)
Flower: Funnelform diurnal, borne in the plant top. Only partly opened just distal portion visible, as they barely stick out above the wool obscured by longer spines at stem apex.
Blooming season:  Flowering late winter-early spring (Feb-Apr)
Fruit: Bright red, thin narrowly cylindric, mm, weakly succulent, soon drying and papery, smooth, spineless; pulp absent; floral remnant deciduous.
Fruiting: Late spring-early summer (Apr-Jun).
 

The cause of cresting: The cause of cresting is not fully explained.   Biologists disagree as to why some plants grow in this unusual form.  Some speculate that it is a genetic mutation. Others say it is the result of a lightning strike or freeze damage. But whatever the stimulus, the growth point of the stem has switched from a geometric point to a line, which folds and undulates as the crest expands. Though these crested cacti are somewhat rare (1 in 50,000 or less), cresting occurs naturally and can be encountered in many other cactus species.
 

E. micromeris (forma texensis) cristata

Grafted on Opuntia compressa

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Origin:  Garden origin (Nursery produced cultivar)

Conservation status: Listed in CITES Appendix II
 

Photo & © copyright by Jürgen Menzel
A crested specimen in habitat

Cultivation: Although regarded as a choice and difficult plant, in cultivation it is relatively easy. It needs a  particularly well-draining soil mix (rot prone). Water sparingly.
Frost Tolerance: Depending on the variety, will handle -12° C (Temperature Zone: USDA 8-11)
Sun Exposure: Light shade to full sun

Propagation: Grafting, cuttings, seeds of crested plants give often rise to some crested plants too.

Photo of conspecific taxa, varieties, forms an cultivars of Epithelantha micromeris:

• E. micromeris
• E. micromeris var. dickisoniae
• E. micromeris var. polycephala
• E. micromeris var. rufispina
• E. micromeris var. unguispina
• E. micromeris cv. ping-pong
• E. micromeris forma cristata