Heteractinida

Heteractinida
Scientific classification
Kingdom:	Animalia
Phylum:	Porifera
Stem group:	Hexactinellida
Informal group:	†"Heteractinida"
Included groups
	See text

The Heteractinids are a grade of sponges that are paraphyletic with respect to Hexactinellida.^[1] Their distinctive trait is their six-pronged (snowflake-like) spicules, whose symmetry historically suggested a relationship with the triradial Calcarean sponges.^[1] Nevertheless, they actually represent a polyphyletic grade, from which the hexactinellids arose.^[1]

References

1 2 3 Botting, J. P.; Butterfield, N. J.; Valentine, J. W. (2005). "Reconstructing early sponge relationships by using the Burgess Shale fossil Eiffelia globosa, Walcott". Proceedings of the National Academy of Sciences of the United States of America. 102 (5): 1554–1559. doi:10.1073/pnas.0405867102. JSTOR 3374469. PMC 547825. PMID 15665105.

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[ref_-1] 1 2 3 Botting, J. P.; Butterfield, N. J.; Valentine, J. W. (2005). "Reconstructing early sponge relationships by using the Burgess Shale fossil Eiffelia globosa, Walcott". Proceedings of the National Academy of Sciences of the United States of America. 102 (5): 1554–1559. doi:10.1073/pnas.0405867102. JSTOR 3374469. PMC 547825. PMID 15665105.