Editing Hyolitha (section)

=== Helens ===
Some hyoliths had helens, long structures that taper as they coil gently in a [[logarithmic spiral]] in a ventral direction.<ref name="Mus2007" /><ref name="ReferenceA"/> The helens had an organic-rich central core surrounded by concentric laminae of calcite.  They grew by the addition of new material at their base, on the cavity side, leaving growth lines.<ref name="Mus2007" />

They were originally described by [[Charles Doolittle Walcott|Walcott]] as separate fossils under the genus name ''Helenia'', (Walcott's wife was named Helena and his daughter Helen); [[Bruce Runnegar]] adopted the name helen when they were recognized as part of the hyolith organism.<ref name="Mus2007" /> Encrusting organisms have been found on helens, and also on both sides of the main shell, all of which are therefore supposed to have been raised above the sea bed. The helens have been interpreted as props that supported the feeding organ, the [[lophophore]], above the sea bed.<ref name="ReferenceA">{{cite journal|last1=Moysiuk|first1=Joseph|last2=Smith|first2=Martin R.|last3=Caron|first3=Jean-Bernard|title=Hyoliths are Palaeozoic lophophorates|journal=Nature|date=11 January 2017|volume=541|issue=7637|pages=394–397|doi=10.1038/nature20804|pmid=28077871|bibcode=2017Natur.541..394M |s2cid=4409157 |url=http://dro.dur.ac.uk/20195/1/20195.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://dro.dur.ac.uk/20195/1/20195.pdf |archive-date=2022-10-09 |url-status=live}}</ref>