| Hyolithellus Temporal range: | |
|---|---|
| Scientific classification | |
| Kingdom: | Animalia |
| Stem group: | Annelida |
| Genus: | †Hyolithellus Billings, 1871 |
Hyolithellus is a conical tubular fossil from the Cambrian, originally considered a hyolith[citation needed] but since reinterpreted tentatively as a stem group annelid worm.
Its circular, thin (15–150 μm), originally phosphatic tube gets wider along its long, undulating, annulated length.