Fig. 1.

Adult skeletogenesis in sea urchin and sea star larvae. (A) Diagram of advanced rudiment stage larva of S. purpuratus (adapted from ref. 13, with permission from Elsevier). (B) Polarized light image of juvenile skeletogenic centers (red dashed area in A), showing spines, plates, and disks of the primary tube feet, elements of the adult skeleton. (C) Diagram of advanced rudiment stage A. miniata larva (modified from ref. 8). (D) Polarized light image of juvenile skeletogenic center (red dashed area in C), showing spines and plates.