https://blogs.scientificamerican.com/artful-amoeba/how-truffles-got-attention-in-a-land-with-no-mammals-to-smell-them/

A truffle is an unsubtle object. These odoriferous, lumpy subterranean fungi -- technically called sequestrate fungi, since their spores are never released to the air -- typically rely on animals to find and eat them, dispersing their spores when they heed the call of nature. If a truffle is in the same room, or, really, the same zip code, you will know about it.

But that is just because they have evolved to appeal to mammals. In a world without mammals, what does a truffle become?