No Mutants Allowed

well first, your skin notices things - thats just some of the things skin do (evolution) and one of the things it notices, is light energy (warmth)

Now you have the material (skin) to notice light! First step! Now you just specialize - you make a valley cone (very first eyes) the invert cone-shape allows for light movement to be followed; if light moves, shadows move too - the skin/cone notices

Now you evolve it, form a cup/jar - just natural progression of the benefit of deeper and more complex cone, to gather light information - finally eyes are a chamber, where light get to bounce around, for maximum data extraction

in the end, eyes aren't special. They're just skin noticing light. Ears are just skin noticing vibration. Skin is just skin noticing... skin...

the tender touch of a loved one