Signs of Life?

"As a NASA spacecraft approaches a dwarf planet in our solar system, Ceres, scientists are stumped by what appear to be two bright lights shining from its surface."


This is interesting. It's probably nothing, but it opens the question (in my mind anyway), of what if we did find a sign of life. 

 How hard would we work to dismiss it? 

 We can say it's probably this or that, but truthfully, at this distance, we really cannot say for sure.

What would it take?