In a game I was playing a while ago I discovered a system with a level 14 nebula. My survey ships had just finished an upgrade so their fuel was nearly topped off and clocks were low. Since the upgrade included an additional two layers of armor I figured I'd have them start surveying and maybe they'd be done before the next refit.
I forgot about the nebula system for a while, then I saw that a hostile contact had been detected in a system name I didn't recognize. It was a 200,000 ton Swarm ship. One of my four surveyors got lucky and was able to escape.