Veseljko replied to Strange thing in water March 4, 2022 @ 3:31:25 am PST
That is serpent. I have seen that on YT channel when the owner of the server made an event for other players. He flew around in debug mode and spawned multiple serpents for an event. As others were approaching we could see exactly what you saw. Serpents unfolded vertically above the water like an antenna (with their heads down). When they came closer, serpents folded back and dropped in the water.
12:13 pm, March 4, 2022