Fig. 7From: Insights into the structure and morphogenesis of the giant basal spicule of the glass sponge Monorhaphis chuniDetails of tuberculate layer (TL) surface in top view and in section. a Well-developed tubercles, close to the AL surface (note complex character of tubercles and small tubercles occurring in between the main tubercles). b Tubercles in cross section showing the transition from the PG surface to the fully formed TL layer. c Tuberculate surface in oblique view to show morphology of tubercles. d Transition from PG layer to low (incipient) tubercles in the TLBack to article page