Some sponges have radial symmetry, but many species are irregular in shape and have no symmetry at all. Two simpler groups of sponges, known as asconoid and syconoid sponges, often have radial symmetry, but members of the most complex group, leuconoid sponges, have no symmetry.
Sponges grow in a unique way: as individual cells surrounded by a matrix of materials they exude. They have the simplest sort of organization among existing animals and have neither organs nor tissues. Asconoid sponges often grow in tube shapes with porous outer walls for taking in water and a large central canal for releasing it. Syconoid sponges are often larger than asconoid sponges, are vase-shaped and have more complex structures to increase their surface area, but otherwise, they have similar body plans to asconoid sponges.
Leuconoid sponges can often grow quite large and have very large surface areas to allow them to move and filter water very efficiently. They have lost the large central canal of other sponges and instead use multiple small canals lined with flagella to release water. All sponges draw in water using the cilia that grow on their individual cells and filter out any food particles present. Some sponges also have symbiotic relationships with algae that allow them to benefit from their photosynthesis.