Just curious. I saw this entity floating out in a sea of jellyfish that I will refer to as "Jellyfish Fields" for no discernible reason, and I found myself wondering if anyone had gotten a group together and tackled it, if it's even possible.

Its part of the OM, not a mob you can kill without doing the first few stages. Im assuming its been killed a number of times as people are constantly getting members to do it in Lemuria. As far as I know, every big mob in the game has been killed at least a few times.

Ah, I didn't notice the open mission/public quest info pop up so I assumed it was just a wandering death-dealer.

It is buggy and doesn't reset properly so not something that people do currently. It is getting fixed with the next patch though.