Driftwood! That's a great addition to an aquarium, providing a natural and rustic touch. Driftwood is wood that has been weathered and shaped by water and sand, often creating unique and interesting shapes.

In an aquarium, driftwood serves several purposes:

- Provides hiding places and shelter for fish
- Creates territories and boundaries for territorial fish
- Acts as a substrate for beneficial bacteria to grow
- Adds aesthetic value and visual interest
- Can help to stabilize water parameters

When using driftwood in an aquarium, it's important to:

- Choose wood that is free of pesticides and chemicals
- Boil or soak the wood to remove any tannins or impurities
- Add the wood gradually to prevent sudden changes in water parameters
- Monitor water parameters and make adjustments as needed

Some popular types of driftwood for aquariums include:

- Mopani wood
- African driftwood
- Malaysian driftwood
- Brazilian driftwood

Remember to always choose driftwood that is suitable for aquarium use and follow proper preparation and maintenance guidelines.