A band of fine ciliary and mucuous-gland tipped spines (clavullae) found in atelostomates. These are used to create ciliary currents within the burrows of infaunal taxa and generate a protective mucous coat. The fine, dense tubercles that support clavullae form a distinct finely granular band on the test (arrowed).
Smooth tubercle- and spine-free channel leading towards the mouth and used for the transportation of fine particles; may be simple or distally branched and usually confined to the oral surface. Found only in clypeasteroids.