Cedar-apple Rust Gall
This fungus has the fancy name, Gymnosporangium juniperi-virginianae, which means "naked spore-bearer of the eastern juniper tree." It's a heteroecious rust, which means that it requires two species of plants to complete its life cycle. Those two species of plants are: the eastern red cedar (Juniperus virginianus) and apple trees (Malus sylvestris). It's also an obligate pathogen, so it can't live without those hosts. It has four different stages, the most impressive of which is the orange teliospore stage because this is when the gall sprouts gelatinous, orange horns that look like tentacles. Pretty impressive. To further add to its coolness, each gelatinous spore horn is actually composed of hundreds of two-celled teliospores.
''Gymnosporangium juniperi-virginianae'' is a plant pathogen that causes cedar-apple rust. In virtually any location where apples or crabapples and Eastern red-cedar coexist, cedar apple rust can be a destructive or disfiguring disease on both the apples and cedars. Quince and hawthorn are the most common host and many species of juniper can substitute for the Eastern red cedars.