Stelletta tethytimeata sp. n. A specimen in situ (BU-533), partially cut to put in evidence the association with Tethytimea tylota. The black arrow indicates the thin layer of the external sponge (T. tylota, orange) while the white arrow indicates S. tethytimeata sp. n. B paraffin-embedded section of T. tylota (t) and S. tethytimeata sp. n. (s) co and ch indicate, respectively, the cortex and the choanosome of S. tethytimeata sp. n. C cross section showing triaenes close to the boundary between T. tylota (t) and S. tethytimeata sp. n. (s) D bundles of oxeas reaching the boundary between T. tylota (t) and S. tethytimeata sp. n. (s) E anatriaene F oxea G micrasters H histological preparation showing the cortex (co) of S. tethytimeata sp. n. The arrow points to the collagenous layer between S. tethytimeata sp. n. and T. tylota (t). The inset shows the layer of tylasters of T. tylota (arrow).