Pareidolia is the psychological phenomena of seeing faces and facial features... When nobody is actually there. Neurotypical brains are hardwired to see patterns, especially those that resemble faces.
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Why? Scientists posit several reasons. The first is: Survival. If you see a creature's face in your surroundings, you're able to react more efficiently to assess and avoid danger. Even if it's *not* another person or creature, your brain can later reassess after potential danger has passed. In other words, better to be safe than sorry!
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Another reason is that our brains are constantly processing new data. We do so more efficiently when we can "fit" new sensory input into existing cognitive boxes, called modules.
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Pareidolia is universal in neurotypical brains. It's why we see faces in many inanimate things (cars, houses, mailboxes...) and can help explain things like ghost sightings. Don't believe me? Scroll to the second photo and tell me that my assortment of jewelry and craft supplies doesn't look like a creepy face.
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Since we are programmed to look for eyes and other facial features in the world around us, it's no wonder that people have also experienced this with stones. Rocks like tiger's eye (shown), malachite, and others have some very eye-like patterns, and are therefore steeped in folklore and legend.
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Specimens with eye patterns are highly prized and have been sought after for centuries. For example, Ancient Mediterranean cultures would use these stones as watchful protectors, often as ways to guard against the Evil Eye