# What do these circles have in common - and what not?

The image below shows 7 x 7 grey circles which all but one share a common attribute. Can you see this shared property, or rather: Can you see which circles does not belong to the group and give a reason?

A complete answer must of course contain an explanation. To identify the circles, simply number them, i.e 3rd column, 5th row or such. I did not want to complicate the image with labels.

Note, you do not need to look at the digital content or super high resolution, nor do you need any digital processing of the image. It also contains only 8 distinct colours.

• That's one heck of a lot of a red herrings – Conor O'Brien Jun 30 '15 at 21:13
• If you miss it then its all over. No solve, Too late. – Bob Jun 30 '15 at 21:18
• This is horribly cruel and I love it. – Deusovi Jun 30 '15 at 23:29

One of the circles

shrinks, the rest do not. This is an animated GIF. The circle in the second row (from the top), sixth column (from the left) shrinks every 60 seconds:

• Quick ;c) I was toying with an yet un-explored property and wanted a time related puzzle. Did you see it, or explore digitally? – BmyGuest Jun 30 '15 at 21:08
• I saw it and thought my eyes might have been playing tricks on me. Then I verified it here. – pacoverflow Jun 30 '15 at 21:09
• Nice and as I hoped/expected. I didn't want to put a longer delay in, as this "puzzle" shouldn't become an annoyance. I wanted to test the idea and if it would work. Didn't expect it to be solved that fast though. (2min before I could accept an answer!!) – BmyGuest Jun 30 '15 at 21:11

Excellent find by pacoverflow but here's a more obvious rule:

All but one of the circles sits on no more than 2 fields of color. The odd circle out, therefore, is 5th row from the top, 3rd column from the left. It sits on 6 fields of color.

With all of the very intentional red herrings, there are probably more rules like that but what pacoverflow found is definitely what was intended.

• With the puzzle specifically mentioning that circle, I think it's pretty clear that it wasn't the intended solution. – Ian MacDonald Jun 30 '15 at 22:06
• @IanMacDonald I missed that reference because it's given as the location. Oh, man, what a twist for a puzzle! Put the actual answer as a throwaway example in the text. I'm going to remember that idea. – Engineer Toast Jun 30 '15 at 22:09
• +1 for the alternative solution. Might have accepted it, if it would have been the first. BTW, my original plan was to have some eye-blinking owls ;c) But I thought people had enough owls for a while... – BmyGuest Jul 1 '15 at 6:28
• @BmyGuest Never enough owls. Mods are asleep. Post more owls. – Engineer Toast Jul 1 '15 at 10:27