[Radiolaria Polycystina] In Nassellaria and Spumellaria: sponge-like (as opposed to latticed) siliceous meshwork of thin, irregular, more or less densely packed bars, mainly in some spumellarian families (Actinommidae, Spongodiscidae).

spongy shell
spongy shell 2
spongy shell 3
spongy shell 4
spongy shell 5
spongy shell 6