I don't uinderstand how people keep seeing convexity in the face of obvious concavity! The only pebbles involved may have been the ones whose fossilization caused these indents

True, it is just water spilled into small holes and the surface tension is making it bulge.

haha dude that's cool i can actually this one unless the mars one. and michael, that's why its an illusion! learn to see it......loosen up! i mean really, its fun!

top one is the real deal due to the line on the left side being in the right proportion

you know what i agree micheal

The shadows tell the story - they're holes.
It's funny though - no matter how you rotate the 2 shots, one always looks like rocks...

when you see holes connected, you know it's holes, not pebbles connected with bridges for unknown reason. water + wind made those holes, i guess.

Deffo one of the coolest so far! effective+simple. haha =].

Clint, water wasnt involved...both illusions are exactly the same, just one is upside down.

I thought they were acne scars...

It's obvious that they're holes, but it's an awesome illusion anyway =)

cool!

ok, so wait, are they all holes?

This is a common illusion when viewing photos taken on Mars or the Moon. People are trained to expect objects to be illuminated from above, so we expect the top image to be holes (shadows under) and the bottom image to be rocks (light from above again, shadows on rock).

But in alien places often times illumination doesn't come from above but from reflections, as is the case on the moon whose dust has the unique property of reflecting light mostly back to its source. (This is because moon dust is composed of little spherules that act like tiny mirrors-- that's why a full moon is 10x brighter than a half moon).

It's possible that the lower image is real only if the shadows created by the 'rocks' do lay on the 'ground' but are contained within the rocks. This is possible if the angle of the sun is just right.

However, the fact that the angle of the sun would have to be different for each of the 'rocks' points to it being the fake. The 'rocks' are convincing taken individually, but not as a collective.

Actually it does work, open it up and seaperate the two halves, then flip one half and view them side by side and they look exactly the sam...

no, no, no. It's an effect that in the bottom one they look more convex, but the top one looks concave. Nice illusion!

cool!!! I love this illusion!!! I like the "acne scars" thing. thats a cool rock. #:0)-/-(

Cool. It is concave, but the second one does look quite a bit like it is convex. It dosen't mater what the explanation is, the point is what it looks like.

To #13: It's a fun illusion, not a science fair. Just enjoy looking at it!

It's obviously the first pic. it has to be this because in the second there are no shadows behind the pebbles.

did anyone else notice the smiley face??? the eyes are on the top picture and the nose and mouth are on the bottom.... and yeah they're holes

anyone notice the phallic shape in ther? x]