Fieldia (named after American businessman and financier Cyrus W. Field) [1] is a genus of worms known from the Cambrian Burgess Shale, and assigned to the priapulids.

[2] It was originally interpreted as an arthropod; its trunk bears a dense covering of spines, and its proboscis is small.

[2] It fed on sea-floor mud, evidenced by the frequent presence of sediments preserved in its gut.

[3] However, the morphological similarity of these organisms to their modern cousins is remarkable, especially for the Burgess Shale,[4] and their similarity to the modern genus Maccabeus suggests that they are in the Seticoronaria stem group, and thus are true crown-group priapulids.

[3] A phylogenetic analysis does not provide a great deal of resolution to the relationships between these basal worms.