It is the largest member of the genus Geastrum (or earthstar fungi) and expanded mature specimens can reach a tip-to-tip length of up to 12 centimeters (4+3⁄4 in).

As the fungus matures, the outer layer of tissue (the exoperidium) splits into four to eight pointed segments that spread outwards and downwards, lifting and exposing the spherical inner spore sac.

The earlier genus name Geaster, introduced by Italian botanist Pier Antonio Micheli in 1727 in Nova Plantarum Genera, is considered an orthographical variant of Geastrum.

[1] Junghuhn, who was living in Indonesia and extensively surveyed its fungal flora, discovered the type specimen on Mount Panggerangi on the island Java, at an elevation between 3,000 to 5,000 feet (910 to 1,520 m).

If it is in fact the same species, the first published name (i.e., G. indicum) has nomenclatorial priority according to the rules of the International Code of Botanical Nomenclature.

More recently, several authors argue that G. indicum should be rejected as a nomen dubium and G. triplex maintained as the correct name for the species.

G. triplex is further categorized in subsection Laevistomata, which includes species with a fibrillose peristome—that is, made of parallel, thin, thread-like filaments.

Hidden from sight are masses of nearly invisible fungal threads called mycelium, which form the active feeding and growing structures of the fungus.

It is composed of a roughly spherical to egg-shaped structure, the endoperidium, topped by an opening, the ostiole, covered by fragments of tissue that form a small pointed beak (a peristome).

Curtis Gates Lloyd claimed that in tropical regions, with an abundance of high temperatures and humidity, the fungus expands rapidly, which is more conducive to the fleshy layer breaking away to form a receptacle; in more temperate areas this effect would not be as pronounced and "usually does not occur at all".

The peristome is made of radially arranged fibrils that clump together at the apex in groups of unequal length to form an opening that appears jagged or torn.

[24] Geastrum triplex may be confused with G. saccatum or G. fimbriatum, as the rays do not always crack around the perimeter to form a bowl under the spore case.

[27] Fruit bodies are often found around well-rotted tree stumps;[25] they are initially almost buried in the loose duff, but emerge during maturity as the downward curling of the rays exposes the spore sac.

[20] A Dutch study reported a propensity for G. triplex to grow on soil made calcium-rich from washed-out chalk of crushed shells on bicycling paths.

[48] The Cherokee put fruit bodies on the navels of babies after childbirth until the withered umbilical cord fell off, "both as a prophylactic and a therapeutic measure".

[50] The fruit bodies of Geastrum triplex have been chemically analyzed and shown to contain a number of bioactive compounds, including fungal sterols such as ergosta-4,6,8,(14),22-tetraen-3-one,5,6-dihydroergosterol, ergosterol, and peroxyergosterol.