With each of the grades of porifera, the skeletal structure is diversifed. In an asconoid, there is usually a predominate tube or sack composition. Along its interior sides, there are uniform and almost parallel canals at intervals. These canals correspond to equivalently positioned porocytes on the exterior layer and passages into the spongocoel in the innermost layers of the sponge. The spongocoel, also referred to as the atrial cavity, is a voluminous central cavity. Directly on the top of the spongocoel is the osculum where water is processed. For its uniform shape, with minimal ability to fold its tissues, porifera of the asconoid grade do not normally grow as large as the two more complex grades.

Syconide sponges are less conforming and recognized as the second most developed grade of the porifera. Porocytes on the outer layers of the sponge maintain their uniform position, but the interior structure is slightly dissimilar. A pear or oval shape, accompanied by more considerable sizes, are usually characteristic of syconide sponges. Within the interior layers, the canals are definitely not as absolutely straight as the asconoids. Instead, they weave within each other, augmenting water flow to more masses of tissue within the sponge. A system is developed within the sponge. By applying this structure, a sponge may extend its surface area. By increasing its surface area, a sponge is more likely to survive and prosper within the environment. It has more developed dimensions.

The leuconoid structure is the result of the influence of time and natural enhancement. Since it is theorized that the leuconoid sponges were the last to eventuate, their structure is far more advanced (in relative terms) than the other two grades. Porocytes are positioned abstractedly upon the pinacocyte layer. Water may flow in more efficiently, and subsequently, this type of sponge will survive better and demonstrate more extensive dimensions and surface area. Internally, a fractal system has been produced in which minuscule canals converge into larger, more centralized incurrent and excurrent canals. While the osculum is still implemented, ostia (Latin for "mouth") also release wastes. An ostium is a side excurrent duct from which wastes and by-products are released by the porifera. In addition, this structure is more suited for change. Such changes occur throughout the day to account for the currents. Such is possible within the leuconoid grade of sponges because of tissue folding.