Geosiphon

Geosiphon is a genus of the Phylum Glomeromycota, Order Glomerales, and Family Geosiphonaceae.

Life cycle
Geosiphon is known for being symbionts with Nostoc forming a Glomales-like fungus, notable for being one of the few non-ascomycete lichens.

It is one of the earliest lichens, containing a "siphonal bladder" that is made of a combination of 2/3 being upper Nostoc filaments and heterocysts, and the lower 1/3 being fungus with lipid droplets.

Reproduction
The spores are 250 micrometres in diameter, formed at the end of one hypha, or between two hyphae and resemble those of Glomus.

Somatic structure
Geosiphon has a specialised bladder used to harbour cyanobacteria, vesicles, but no arbuscles.