There are reportedly worlds in the Solar System that may host life in seas underneath a global ice sheet.
After watching this video, all I can say is, those moons have a ways to go before they can match Earth!
Per the note accompanying the video, that was filmed in the White Sea.
And I am sorry to harsh your mellow, but Wikipedia calls that ethereal beauty a sea slug!!
I prefer its more common name: sea angel.
Featured image: Matt Wilson/Joy Clark, NOAA NMFS AFSC via Wikimedia, public domain.
Flight To Wonder 