One hundred and seventy seven living and dead complete tests of Jacksonaster depressum (L. Agassiz)
were collected from different depths ranging between 10 and 52 meters depth from the Northern Bay of
Safaga, Red Sea coast. Morphometric measurements were conducted on some specific characters of the
skeletons in addition to use the scanning electron microscope in the study on spines, tubercles,
ambulacral pores, and pedicellariae. The internal partitions, oral and aboral plate patterns, predation
and failure growth of the test have been examined and reported. Five types of pedicellariae are recorded
herein: ophicephalous, triphyllous, tridentate, and the two new types Pharaonic columns-like and cigarlike.
Distribution of the complete living and dead tests related to water depths and both bottom and
sedimentary facies of the study area are given. It is clear that the Red Sea environment, especially Safaga
Bay, is more severe and of a lesser quality than that of the Pliocene Epoch and than the current seas
especially that found in Mauritius, in which the species present.