|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.
|W. Hantzschel 1975||Sideritic and phosphoritic concretions of cylindrical, pyriform or subspherical shape with an axial straight unbranched tube; concretions 3 to 30 cm long, 2 to 15 cm wide, primarily found with vertical orientation in fine marine sands and usually occurring in groups; tube 1 to mostly 3 mm in diameter, with segmentation intervals of 2.5 to 6 mm, each segment exhibits very fine transverse annulation with striae at intervals of about 0.2 mm, tube ending in small flat chamber near bottom of concretion, but lower part of tube often continues more indistinctly downward several decimeters into underlying sediment.|