Editing Hexactinellid (section)

=== Longevity ===
[[Image:Venus Flower Basket.jpg|thumb|[[Venus' flower basket]], ''Euplectella aspergillum'']]
[[File:Glass-sponge, Euplectella aspergillum.jpg|thumb|Euplectella aspergillum]]
These creatures are long-lived, but the exact age is hard to measure; one study based on modelling gave an estimated age of a specimen of ''[[Anoxycalyx joubini|Scolymastra joubini]]'' as 23,000 years (with a range from 13,000 to 40,000 years). However, due to changes in sea levels since the [[Last Glacial Maximum]], its maximum age is thought to be no more than 15,000 years,<ref>{{cite journal
 |author=Susanne Gatti 
 |year=2002 
 |title=The Role of Sponges in High-Antarctic Carbon and Silicon Cycling - a Modelling Approach 
 |journal=Ber. Polarforsch. Meeresforsch 
 |volume=434 
 |issn=1618-3193 
 |url=http://epic.awi.de/Publications/BerPolarforsch2002434.pdf 
 |access-date=2009-05-25 
 |url-status=dead 
 |archive-url=https://web.archive.org/web/20110724175156/http://epic.awi.de/Publications/BerPolarforsch2002434.pdf 
 |archive-date=2011-07-24 
}}</ref> hence its listing of c. 15,000 years in the AnAge Database.<ref>{{cite web| url = http://genomics.senescence.info/species/entry.php?species=Scolymastra_joubini| title = Hexactinellid information from the AnAge Database}}</ref> The shallow-water occurrence of hexactinellids is rare worldwide. In the [[Antarctic]], two species occur as shallow as 33 meters under the ice. In the [[Mediterranean Sea|Mediterranean]], one species occurs as shallow as {{convert|18|m|ft}} in a cave with deep water upwelling (Boury-Esnault & Vacelet (1994))

<gallery widths="200px" heights="200px">
File:Staurocalyptus- noaa photo expl0951.jpg|''[[Staurocalyptus]]'' sp.
File:Hexactinellida.jpg|Various hexactinellid sponges.
Image:SpongeXenophorid.jpg|Hexactinellid sponge on a [[Xenophoridae|xenophorid]] gastropod.
Image:Pattersonia ulrichi Rauff, 1894.JPG|''Pattersonia ulrichi'' Rauff, 1894; an Ordovician hexactinellid sponge from near Cincinnati, Ohio.
</gallery>