The Yellow Sponge, or Cleona Celata, is one of the most common sponges in Africa. Its has many rough and thick "tubes", connected at their base. The tubes are always in a vertical or near-vertical appearance and appear bright yellow in shallower water, although it may be darker yellow to orange in deeper water. This has to do with both the temperature and the light entering the water. Sponges cannot move around, so they have to be hard enough to resist predators. They are filter feeders, and rely on microbial organisms getting close enough to them to be able to feed on them.