| The Polychaeta lack a clitellum and have parapodia, paddle-like appendages with numerous bristles or chaetae. |
| A newly described machaeridian fossil from Morocco was found with rarely preserved soft parts, including parapodia and chaetae. |
| A row of long acinaciform chaetae occurs ventrally along the margin of each lateral lobe. |
| The microscopic structure of the setae is identical to that of the chaetae of polychaete worms. |
| A major feature of all annelids except leeches is the possession of bristles, or chaetae, of which there are many varieties. |
| In this respect, as indeed in their microstructure, the sclerites of Wiwaxia are fundamentally more comparable to polychaete chaetae. |
