Feather Stars or Crinoids are the most ancient of equinoderms. They anchor inside narrow crevices with only their arms (broken arms can be regenerated) and they adhere tightly to anything that comes into contact with them.
Sea Stars, usually have 5 arms (broken arms can be regenerated), the mouth is located on the undersurface and on the top the anus.
Sea Urchins, have spherical bodies with long protective spines. Mouth is underside and anus on the top. Spines easily puncture the skin and break in the flesh causing a painful wound.
Sand Dollar, are irregular echinoids, on the back they show a five–petal sculptured design. They live under the sand, their skeletal remains, rather than the living animals, and this skeletal is what we found on the sand while diving.
Sea Cucumber, have a sausage–shaped bodies with a mouth in front and anus at the rear. The 5 body–sections common to all equinoderms are not visible in these animals but are part of their internal structure.