Answer:
Basic characteristics of Sponges:
Sponges belong to phylum porifera. They are simple multi-cellular aquatic animals. They have pores in their body thats why they look like sponge we use in kitchen. These pores are known as ostia. The body cavity is known as spongocoel, which open to out side through large pore known as osculum. Their body is composed of two layers, choanocyte and pinacocyte. Choanocytes are flagellated cells having spikes which help in movement of water into body and aid in capturing of food particles. The skeleton is made up of calcium carbonate or silica. A jelly like substance called as mesoglea is present between pinacocyte and choanoderm.
General characteristics of Archeocyathans:
The term archeocyathans is a Greek word for "ancient cup". They have a single common ancestor and became one of the planet first reef animals. Species of archeocyathans is divided into two classes, six orders, 12 suborders, 120 families and nearly 300 genera. They are associated with carbonate sedimentation.They generally lived in shallow water with photic zone. Their fossils often co-occured with fossils of cyanobacteria. These are marine organisms whose fossils record dated back to late Precambrian and early Cambrian period. They are most closely resemble to calcareous sponges. Their structure s are conical or tubular in shape and superficially resembles horn reefs. They have world wide distribution and found in Australia, Antartica, Spain, Cubec, New york and California,
