As one of Earth's closest neighbors in space, Mars has long captivated humans with the prospect of alien life located just a short rocket trip away. No such life has been found. But now, as NASA and other space agencies have begun to explore the skies and surface of the Red Planet using robotic technology, images of strange features and formations continue to inflame skywatchers' hopes, fears and curiosities.

Here are some of our favorite objects on Mars that look like they don't belong on a dead and dusty planet. Many of these are a result of pareidolia — the tendency for humans to seek familiar patterns and shapes in inanimate objects. However, some of them may even lead scientists to the long-sought evidence of past Martian life.

There are a lot of questions about Mars that need answering.

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