 Similar to other Discomycetes, the fruit body consists of three distinct layers of tissue: the hymenium, the hypothecium, and the excipulum. The spore-bearing hymenium, the outermost layer of cells, contains asci interspersed with sterile cells called paraphyses. In C. geaster, the club-shaped asci are 700 – 800 µm long and 14 – 17.25 µm thick; they are abruptly constricted at the base to a narrow pedicel. The paraphyses are initially filamentous or thread-like (filiform) but swell with age to resemble a string of beads (moniliform). The swelling of the paraphyses is believed to cause the expansion of the hymenium and subsequent splitting of the fruit body into rays; this development places the asci into an optimal position for spore release and dispersal. Supporting the cells of the hymenium is a thin layer of tightly interwoven hyphae called the hypothecium, and underneath this is a thick layer of loosely interwoven hyphae known as the excipulum. This tissue layer, analogous to parenchyma found in plants, gives the tissue a fibrous texture. The excipulum layer averages 34 µm in diameter, while the hypothecium is 10 – 14 µm. When viewed with electron microscopy, the dark brown "hairs" on the surface of the fruit body can be seen to be adorned with conical warts or spines.
