- Mold is a kind of fungus
- In the food chain process fungi have the role of decomposer
- So, in the food chain mold has the role of decomposer

Hence, in the food chain mold has the role of decomposer
Q: Mold is often found growing on old bread. In a food chain, mold is a ___.
Context:
- Mold is a kind of fungus 
- In the food chain process fungi have the role of decomposer