The folks at RankRanger spotted and posted on Twitter Google testing a new form of query expansion for related queries under the featured snippets. We saw this before about a year ago but it hasn't come up much since.
In short, Google is listing other queries, that help the searcher expand and refine their search to give you a more precise and detailed featured snippet answer.
Here is a screen shot which you can click on to enlarge:
No surprise here of course...
Forum discussion at Twitter.
