Saad also spotted back in March Google testing showing that bell icon feature directly in the image search carousel box. The bell icon lets you tell Google you are interested in being pushed information about that topic via Google Discover and maybe Google Alerts (in the older days).
We've seen the bell icon for a while now but on image search carousel boxes - well, that one seemed weird. Saad posted this and the more specific searches item back in March on Twitter, and for some reason I missed covering it. So here it is:
Again, this is super weird to see on an image search results box.
Forum discussion at Twitter.