Bubble Navigation?

I would like to use a concept similar to what is found on http://hashtagify.me/. I don’t know what the concept is officially called but I what to create a pseudo-navigation using this “bubble” type of interface. For example, 2016 may be the center of the bubble with the months extending from the center. Drilling into a particular month will show the weeks. Drilling further will then show days, hours, etc. Within each “bubble” would be the ability to link to a post or page.

Has anyone ever seen anything like this? I’m looking for any direction anyone may have. Even if it is simply the name of the type of interface Hashtagify uses.