Northern Blood Kelp ghost leviathan vanished.

I've been building a base in the Northern Blood Kelp biome and noticed that the ghost leviathan there just completely vanished. I saw him once using the seamoth sonar when I was first in the area, then he swam out of range and I haven't seen him since. I decided to use freecam to see if he was just stuck in the terrain or something and found him (I assuming it's him) underground near the meteorite crater in the dunes. I have no idea how he got there lol.