Fossilight

The Fossilight is the high end of the spectrum: a Divine, limited, multi-harvest crop and, per its own description, the rarest seed in the Ancient Seed Pack from the Prehistoric Event. That single fact reframes its entire economics. You almost never "buy a seed" in the normal sense here, you gamble for it inside a pack, so the true cost is every pack you opened chasing it. Pulling one is the win; the sell price of its produce is almost secondary.

Two type tags make the Fossilight genuinely strong rather than just a trophy. It is both Prehistoric and Magical, so it benefits from two separate families of boosting items and pets at once, something most single-tagged crops cannot do. Combined with multi-harvest, that means one lucky pull keeps paying across many cycles, and any mutation you land, Gold, Rainbow, or a stacked event mutation, lands on a Divine base that already commands premium value.

Progression-wise this is a late-game flex. Do not chase the Ancient Seed Pack for it until you have surplus currency, but once a Fossilight is yours, protect it, mutate it, and never sell the plant itself.