Rexiella sullivanii

About

Rexiella is a small lichen genus in the family Cladoniaceae. The genus was originally established in 2018 but had to be renamed in 2019 because the original name conflicted with an earlier genus of cyanobacteria, with both names honouring Australian lichenologist Rex Filson. These shrubby lichens form upright, horn-like stalks that are riddled with window-like holes and have a distinctive dark grey to black interior filling, distinguishing them from similar-looking relatives.

Summary from Wikipedia