Also known as Humble Sea Biscuit, Cake Urchin, Flattened Sea Biscuit
Humble sea biscuits creep slowly across shallow sandy seafloors, using thousands of coordinated tube feet and specialized spines to sift through sediment for organic matter. Their flattened, pentagonal tests display distinctive petaloid patterns on the upper surface that house specialized respiratory tube feet for gas exchange in warm Indo-Pacific waters. By plowing gently through the upper layers of sand, they aerate lagoon sediments and support nutrient recycling across reef flats.
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