There is some chatter that Google is testing adsence ad arrows with different shapes like “square boxes” “round edged” “no arrow” and “even a rectangular boxed in arrow”. The same can be seen in below screen shot –
According to “wordmasterworld” conversation Google is unhappy with the performance of ad formats as not earning much with it. They are worried and testing the different versions for the sake of earning lot money. The testing is too unreal as it is the prime time for publishers to earn through adsence.