> For the complete documentation index, see [llms.txt](https://docs.chikn.farm/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.chikn.farm/nfts/roostr-nft/architecture.md).

# Architecture

Everyone knows that chikn lay $EGG, and Roostr squirt $FERT. The need to rhyme is stronger than we are.

Roostr produce the all-important $FERT—a token that can be used to improve FarmLand reward yields among other things. For more information on what $FERT can be used for, see the section on[ $FERT](/tokens/fert.md).

To produce $FERT, Roostr need to eat $EGG. These protein-rich ovals pass through the Roostr’s digestive system, helping them grow bigger and coming out the other end as $FERT.

<figure><img src="/files/L5b77P3SVJWlgPNUChZa" alt=""><figcaption><p>The $FERT Cycle - animation by <a href="https://twitter.com/thelinhhoang">linsanity</a></p></figcaption></figure>

Roostr bring added complexity to the Chikn game and give players the opportunity to optimize their Farming strategies. With the rollout of Foraging introducing new ways to spend $FERT, Roostr themselves have become even more important in the broader meta.