Final answer:
When Tom buried his pet fish in the soil, it decomposed over time due to natural processes. The fish's body would not be visible when the soil was dug up because it had completely decomposed.
Step-by-step explanation:
When Tom buried his pet fish in the soil, it decomposed due to natural processes. Decomposition is the process in which organic matter breaks down into simpler substances like water, carbon dioxide, and nutrients.
Bacteria, fungi, and other organisms assist in this process by breaking down the fish's body and recycling its nutrients back into the soil.
Over time, the fish's remains would have turned into organic matter, enriching the soil with nutrients.
When Tom dug up the soil after a few months, the fish's body would not be visible anymore because it had completely decomposed.