Confusing black spot found. Can anyone please explain what it might be?

Sorry if this is not the correct way to post on here, I'm very new to this. I was messing around on Wikisky.org after learning a bit about NGC 4993 when I zoomed out by mistake and noticed something a bit odd. I highlighted what I found in the image and also the nearest documented object (not sure what the correct terminology would be). If anyone could please be able to explain what I found might be, It would be much appreciated. EDIT: https://imgur.com/a/UO9nM