[citation needed] Heliophora orbicularis live in large groups in very shallow water of lagoons and estuaries, usually lightly buried in mud.
The sand dollar is part of the phylum Echinodermata, and so the organism has an endoskeleton composed of calcareous ossicles which grow from the mesodermal tissue.
Equally important, as echinoids living on an unstable sediment surface swept by waves and currents, their form minimizes drag and facilitates maintenance of position.
[3] However, their low, domed profile acts as a hydrofoil and generates lift, which could send the sand dollar flowing into a harsh current.
[3] West African Sand Dollars also have small spines that help them sieve food particles from sandy or silty sediments.
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.
The reason this adaptation is beneficial is because sand dollars with higher growth rates also have higher mortality rates, which suggests that either the larvae did not use a significant amount of lipid energy reserves to survive or that energy reserves are not critical for the survival of the larvae.
Another reason this adaptation is beneficial is because newly metamorphosed sand dollars are extremely vulnerable to tube-building predators such as Leptochelia dubia.