Gemini Mention
This capsule allow visitor to submit a gemini mention.
It means submitting a URI to a valid gemini page that contains a link to any pages of this capsule.
Gemini mention are a way of alerting capsule owner that you wrote a response to one of their content on your own gemlog. It doesn't require sharing email address or anything. Just a valid link.
If you interested in the origins of gemini mention, you can read the following gemlog entries:
Source