[4] Fissurina elixii has a pale olive-grey, glossy, continuous, and cracked thallus that is 40–100 μm thick and forms irregular, diffuse patches up to 60 mm wide, without crystals of calcium oxalate.

In cross-section, the exciple is poorly differentiated from adjacent tissues, varying in thickness and colour from hyaline (translucent) to yellowish laterally and basally to brown-black or olive-black apically, with numerous periphysoids (hair-like structures) at the margins.

The ascospores are broadly ellipsoid with rounded apices, transversely 3-septate (with three cross-walls), typically measuring 16–26 by 8–11 μm, and has a pale blue staining reaction to iodine when mature.

[5] Fissurina elixii has been documented growing on the trunks of Anopterus glandulosus and Tasmannia lanceolata trees within relic stands of Atherosperma-dominated rainforest located in southeastern Tasmania.

What sets Fissurina elixii apart from other Tasmanian species within its genus is its unique chemical composition, specifically the presence of substances structurally related to psoromic acid.