Facivermis is a peculiar genus of Cambrian worm which had ten prickly arms, five on each side of the head area. Fossils of Facivermis are rare and are found in China.
The image below shows a fossil with many specimens of the spiny worm Corynetis brevis and one Facivermis yunnanicus. In this fossil, Facivermis is holding its ten arms against its body, possibly so they wouldn't get in the way of burrowing.
Facivermis may have used its arms to grab prey, but that's just my hypothesis.