+1 Kate

To add on what Kate said, you can typically get a little more data to help you pinpoint what it is by clicking on other and then looking at secondary dimensions such as medium, ad distribution network, placement domain, campaign, etc.

As everyone else has said, it doesn't really make a difference whether you have a file/extension as part of the URL. But if you do change your URLs and 301 redirect the old URLs to the new, you will lose some link equity (typically about 10%-15%); I'm not sure if this devaluation is reflected in OSE/Moz metrics.

That said, I would recommend showing the directory without a file extension (using consumerbase.com/ instead of consumerbase.com/index.html). If you change platforms in the future to something that runs off PHP or some other language, displaying .html file types might not be an option but you can always display the directory. If you set yourself up now to display without the doc type, you don't have to worry about these changes in the future as much.