|Basic info||Taxonomic history||Classification||Relationships|
|Morphology||Ecology and taphonomy||Age range and collections|
Helicoplacoidea - Helicoplacidae
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.
|J. W. Durham 1967||Test with numerous pleats, possibly as many as 18 to 20; pleats apparently expansible, produced into numerous regularly spaced conical protuberances on margin, giving scalloped appearance; ambulacra unknown.|
|J. W. Durham 1993||Test built of a mosaic of numerous small plates arranged in expansible pleats that spiral around central axis like those of other helicoplacoids. Ambulacra unknown.|
|B. C. Wilbur 2006||Helicoplacoids with interambulacra composed of fused basal plates in the shape of a pentagon, and twice as many distal polygonal plates.|