Between mushroom and train, I’d prefer to use mushroom

Mushrooms are important for maintaining and developing ecosystems through their interactions with nature:

• Recycling Role: Mushrooms break down dead plants, animals, and trees, acting as recyclers in the ecosystem.
• Symbiotic Relationship with Plants: Mushrooms form symbiotic relationships with plants. They absorb nutrients from the soil and supply them to the plants, while plants provide carbohydrates produced through photosynthesis to the mushrooms.
• Interaction with Animals: Some animals eat mushrooms and, in the process, spread the mushroom spores to other areas, helping mushrooms to reproduce.
• Indicators of Climate and Ecosystem Health: Mushrooms are important indicators of the state of the climate and the ecosystem.
• Interaction with Microorganisms: Mushrooms interact with microorganisms, helping to control bacteria and fungi in their environment.

maya/houdini

vivid color, various shape, spore cloud(- particle or smoke)

Environment: Ancient forest

Also want to use a giant mushroom as a guardian deity

There’s an ancient forest in Japan. A researcher A who lives in Tokyo, studies nature (or forests or ancient cultures). She lost her parents when she was young and has no memories of them. While researching, she comes across a book about giant mushrooms that live in the ancient forest. She knows that these creatures absorb human memories and emotions. To recover her lost memories, A sets out to explore the forest. As she delves deeper into the heart of the forest, she begins to experience fragments of her lost memories. In the depths of the forest, she encounters the memory-absorbing mushrooms.