Hallirhoidae

Taxobox
name = Hallirhoidae
fossil_range = Cretaceous - Eocene

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image_caption = Various Cretaceous Hallirhoiids
regnum = Animalia
phylum = Porifera
classis = Hexactenellida
ordo = Lithistida
familia = Hallirhoidae
subdivision_ranks = genus
subdivision =
*"Hallirhoa"
*"Siphonia"
*"Callopegma"

Hallirhoidae is an extinct family of lithistid demosponges found throughout the world from the Cretaceous to the Eocene, whereupon they went extinct. The highest concentration of species occurred in the Tethys Ocean during the upper Cretaceous. The hallirhoid demosponges were very distinctive-looking, largely pear-shaped sponges that were attached to the seafloor by a long stem-like stalk.