|Basic info||Taxonomic history||Classification||Relationships|
|Morphology||Ecology and taphonomy||Age range and collections|
If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.
|S. Conway Morris and A. J. Chapman 1997||Bilaterally symmetrical shell, thin, concavo-convex but may have upturned rim, phosphatic. Small apex with transverse furrows imparting segmentation. Shell bears fibroplacodes, arranged in ten rows (five pairs). Each fibroplacode consisting of a subcircular area housing fibrous body, capped by smooth disk.|