Eusthenopteron

The Eusthenopteron is a stand-alone fossil that can be donated to the museum in.

In New Horizons
"The Eusthenopteron is famous for being the link between fish and land animals long before dinosaurs. It seems to have strong fins capable of pulling it around areas where the water was shallow. When most creatures lived in the sea... they dreamed of land. If not for them, we mightn't be here today! Imagine if we'd not left the oceans... How might fashion and music be different in an aquatic world? How would we resolve differences? Perhaps some sort of ink-squirting contest of champions? " —Blathers