matrix
From ZooTerms (Dictionary of Invertebrate Zoology)
matrix (noun; plural matrices; Latin mater, mother): 1. That which gives form, origin or foundation to something enclosed or embedded in it.
2. (NEMATA: Secernentea) The gelatinous substance secreted by some female nematodes into which eggs are deposited to form an egg mass.
3. (Platyhelminthes) In Cestoda and Trematoda, a living interface of interacting photoplasmic layer; part of the syncytium of the tegument.
4. (Porifera) The non-cellular ground material of a sponge in which the cellular elements are dispersed.
