An obelisk is a "viroid-like element" of a type first described in a January 2024 preprint, whose authors say that "Obelisks form their own distinct phylogenetic group",[1][2][3] as their RNA sequences, discovered by computer-aided metatranscriptomics, are not homologous with the genomic sequence of any other life form.[1] Currently, only a few methods are available for the identification of these elements from NGS data.[4]
With their relationship to other organisms being unknown, they are an example of the incertae sedis, or "enigmatic taxa".