Echinoderms received great attention in various scientific applications due to their unusual regenerative characteristics. Clypeaster humilis is the animal of choice in this study. Most of the published scientific research papers are concerned with the morphology of the animal, larvae and internal organs; nothing dealt with the cellular or chemical constituents of the animal coelomic fluid. Although the coelomic fluid (haemocoel) represents a vital component filled with many important constituents, few publications were published concerning this issue.  Clypeaster humilis is also known as sea biscuits/sand dollars. This invertebrate animal was collected from Hurghada, Red Sea, Egypt. This study brings new knowledge of recording and documenting the obtained scientific data concerned with one of the poorly-studied phyla of the Egyptian fauna. The coelomic fluid of the sand dollar was chemically analyzed, and the obtained data revealed the presence of glycogen synthase kinase3-β protein by protein docking, which is essential for wound healing. In addition, the ultrastructural investigations detected two types of cells; namely, young and mature coelomocytes, and the latter is divided into secretory granular and secretory mucous cells, respectively. The coelomic fluid extracted from C. humilis exhibits glycogen synthase kinase3-β protein, which could be a promising constituent for many medicinal applications including wound healing in diabetics. All coelomocytes are differentiated from the young or progenitor coelomocytes, which then might harbor different secretory materials and turned into secretory granular and secretory mucous coelomocytes.