Small, cylindrical, sycon-type sponges common in shallow marine waters. Sycon-type sponges are intermediate—in terms of morphological complexity—between the simplest bag-like sponges and the intricate architecture of the leuconoid sponges. The phylum Porifera can be viewed as occupying middle ground between the colonial flagellates and the true multicellular animals. Evolutionarily, however, they probably represent a dead end. Size range is ½" to ¾" in length.