The non spicutar skeleton of the genus
Merlia may be absent and a new species,
M. deficiens, is described. A part of
the recent Porifera may be the descendent of fossil calcified organisms (Stromatoporoids, Chaetetids... ) which have lost
their calcareous skeleton. Size cells packed in cavities of the skeleton are similar to gemrnular cells, a fact which may
explain the occurrence of discontinuities in the skeleton of some Stromatoporoid fossils.