Whenever I candle, I sniff each egg while I'm at it. The more you candle, the more confident you'll be when tossing out the non fertile, the cracked and porous and the quitters. When unsure, put it back in the bator and check again in 3 days time. If it looks the same, toss it. To keep up with which egg looks like which, feel free to draw on your eggs. If you candle and see a blood ring or blood spot, mark it. That way if you choose to incubate a few more days, you'll know if it has changed any based on your previous drawings. Even keep a little chart if it helps. Label your eggs A, B, C ... and make notes about each every time you candle and eventually you may not need the chart as your experience and confidence grows.
And that egg is considered to be extremely porous and bacteria most likely invaded early on and prevented development or it was not fertile to start with. Feel confident knowing if there are no vessels, there is no life and toss that one.