Yggdrasil

"'In your last moments you saw God. After being absorbed it called for more. The oceans outside trembled and quaked, for the next clueless victim to be awakened.' - Templum Inundatio's ending text" Yggdrasil is the Hivemind of the Moss Men and the creature that summons the Water Buddies in Templum Inundatio. Located in the temple, he is a moss-like creature that absorbs any kind of water to grow in size and power. He specifically targets Water Buddies, which are a species of formed water from the ocean, to enter the temple to be absorbed by him. Water Buddies that are absorbed by Yggdrasil are turned into Water Buddy Corpse Cubes.

Story (Templum Inundatio)
In Templum Inundatio, Yggdrasil is the creature that emits the sounds that causes the Water Buddies to form from the ocean and explore the temple.

At the end of the game, you encounter Yggdrasil, who absorbs you like all of the other Water Buddies to grow in power so he can break out of the temple and absorb the oceans of the world completely.