Sand Dollar has a feeding device called “Aristotle’s lantern.” Aristotle’s lantern is a complex system of jaws and muscles which are capable of a variety of feeding types including suspension feeding, herbivory and detritivory feeding, and occasionally predation. Adaptations to this lantern have allowed sand dollars to live in habitats which have fine, shifting substrates. Just like other sand dollars, the West African Sand Dollar has a shallow dome with a thin edge that is ideal for burrowing. Equally important, as echinoids living on an unstable sediment surface swept by waves and currents, their form minimizes drag and facilitates maintenance of position. However, their low, domed profile acts as a hydrofoil and generates lift, which could send the sand dollar flowing into a harsh current. One adaptation to this generation of lift is the presence of lunules. Lunules reduce lift by interfering with attachment of flow or by bleeding off pressure from the under surface. Excess pressure on the oral surface of lunulate sand dollars is relieved by flow along pressure drainage channels which lead from the central region of the disc into the lunules and ambital notches. It is also hypothesized that lunules shorten the food path of sand dollars, however this is not fully supported by observation. West African Sand Dollars also have small spines that help them sieve food particles from sandy or silty sediments. These spines have lost their protection function and are used more for burrowing and feeding. Types of sand dollar spines include: Shoe spines (broad and tuberculate), Ambulatory spines (longer than shoe spines on lower surface), frill spines (flatter than ambulatory and larger), non-ambulatory spines (food collecting spines of ventral surface), and miliary spines (small and short). Delayed metamorphosis The West African Sand Dollar, just like all other sand dollars, is capable of delaying metamorphosis for a limited amount of time. One study by Raymond C. Highsmith and Richard B. Emlet studied two sand dollar relatives of the West African Sand Dollar during the delayed metamorphosis period, testing with differing lengths of time in replicate fed and unfed treatments. Their results showed that spontaneous metamorphosis increased gradually during the first 3 weeks of competence, peaked sharply in the fourth week, and then declined to approximately 20% for each of the remaining 3 weeks. Their evidence also supports that growth rates of juveniles from weeks 2 and 4 that were maintained at 20 °C