Fig. 8From: Insights into the structure and morphogenesis of the giant basal spicule of the glass sponge Monorhaphis chuniAnnular layer (AL) surface. a General view; note that some ridges split or branch. b Details of ridges that are tuberculate and intercalating with lower ridges. c Details of the AL surface showing spinose ridges. d Details of broken spines as in c, to show that they are empty internallyBack to article page