† oxytetractn. and adj.Obsolete(a) n. a sponge spicule having four pointed rays radiating from a single point;(b) adj. (of a sponge spicule) having four pointed rays radiating from a single point.
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1886 R. von LendenfeldSponges in Proc. Zool. Soc. 562Oxytetract. Two rays rudimentary, representing the edges of a square pyramid.