Reefback Leviathan

The Reefback is a life form belonging to the fauna category.

It is massive in size (see comparison with Seamoth in the gallery) and very slow. It appears to patrol the sea mostly in herds of more than two. They appear to be a hybrid between a whale (for their prodigious size and calls) and a Portuguese man o' war (for their purple, humped backs, tails, and strange underbellies). They rarely come up to the surface in which you would be able to stand on its head.

Its attitude is passive, and the Reefback appears to be cathemeral (active both at night and during the day).

Reefbacks are currently found in the Mushroom Forest and Grassy Plateau Biomes.

Due to their dark top they are not always easy to spot. However, the Reefback is bioluminescent and very audible, owing to its low-frequency, loud calls, which are similar to a whale's.

Speculation
As seen in the concept artwork, it is possible that the Reefback will shelter an entire and unique ecosystem on it's back.

The Cyclops submarine can emit a low-frequency noise similar to the Reefback 's calls. It is possible in the future that there might be an interaction between the two. Right now, Submarine's horn attracts Reefback to it, so be careful not to use it below 100 meters, or it could damage Cyclops.