Arguably the most important discovery in Jules Verne's Journey to the Center of the Earth is the twelve-foot-tall, humanlike creature Otto and Axel encounter during their journey beneath the surface of the earth. This creature looks like a human being in many ways, but not in others. It is watching a herd of mastodon, perhaps in the role of a shepherd. The men are not sure if it is an apelike man or a manlike ape, but they decide not to wait around to find out, for they are also not sure how the creature will react to them. Later, Axel wonders if the creature was real or if he only dreamed the incident.

The creature is important if real because it presents a possible stage in human evolution or another branch of the human family. The men, however, can bring back no proof of their discovery, for they do not dare approach the creature. Just seeing the creature, though, is enough to inspire wonder and curiosity for a long time to come.

Otto, Axel, and Hans make plenty of other important discoveries throughout the novel. Otto's initial discovery of the coded document in the manuscript is highly important, for it begins the entire journey. The discovery of the underground cavern inside the volcano is crucial, as well as is the discovery of the initials A.S., for they prove the authenticity of the document. The group also finds fantastic geological features, huge mushrooms, and creatures that have long been extinct on the earth's surface. All of these lead to an increase in knowledge and a broader view of the world from the inside out.