Read the new Scientitic American blog entry by Avi Loeb, 

"Progress in science is sometimes triggered by surprises. Data collection resembles gathering of new pieces in a jigsaw puzzle and placing them together. Sometimes one of the pieces does not quite fit. It is natural for scientists to instinctively argue that such a piece does not belong; perhaps it is an artifact driven by uncertainties in the data or a misinterpretation of the experiment."

https://blogs.scientificamerican.com/observations/the-power-of-anomalies/