Asterias. The model shows:

• 1. Complete arm with normal position of the organs (stomach, intestinal caeca, pyloric caica, ampullae)
• 2. Arm with ampullae, ring canal, Polian vesicles
• 3. Skeleton of the arm with nervous system (nerve-ring and radial nerves)
• 4. Arm in transverse section (ambulacral system in cross-section)

The cut surface shows the stomach, stone canal, axial organ and madreporite. In addition on the outside the podia, pedicellariae and optic organs are shown.