Hyolithellus is a conical tubular fossil from the Cambrian, originally considered a hyolith but since has been reinterpreted (tentatively) as an annelid worm. Its circular, thin (15–150 μm), originally phosphatic tube gets wider along its long, undulating, annulated length.
Species taxanomy provided by GBIF Secretariat (2022). GBIF Backbone Taxonomy. Checklist dataset https://doi.org/10.15468/39omei accessed via GBIF.org on 2023-06-13; License: CC BY 4.0