Definition of "membraniporiform"

[M]any species having eschariform zoaria in quiet water are able to assume the membraniporiform habitus in strongly agitated water.

1963, Alan H. Cheetham, Late Eocene Zoogeography of the Eastern Gulf Coast Region, page 30

All species having non-fenestrate, rigidly erect colonies, with either subcylindrical or bilaminate trunks and branches (vinculariiform and eschariform colonies, respectively), or closely encrusting (membraniporiform) colonies were regarded as unstable.

1971, Smithsonian Contributions to Paleobiology, page 6