Bull ant

The Bull ant is a level 40 Summoning familiar, and can carry up to 9 items. It cannot hold Untradeable Items nor can the nine items it holds be worth up to more than 450,000 coins. It cannot hold Rune essence or Pure essence.

It is summoned by using a Bull ant pouch, which will give you 0.6 Summoning experience. Apart from being able to Store up to 9 items for you temporarily, it also has a special move called Unburden that restores running energy based on one's Agility level, which can be activated if you have a Unburden scroll in your inventory. The amount of run energy restored is half of your Agility level. The Bull ant is immune to poison damage. It originally could only hold 3 items but this was increased to 9 with the Summoning 2 update.

Unburden scroll
Unburden scroll enables the use of the Unburden special move for a Bull ant. Using the pouch on a Summoning obelisk creates 10 scrolls.

Unburden
This special move restores a player's run energy by half of their Agility level. It is very useful for running for long periods of time.