Description (from Bestiary)
"Bottom-dwelling fish, lives both in salt and freshwater. Will often bury itself in the mud at the bottom with only the head sticking out. Not aggressive, but has a poisonous sting that will severely injure anyone who steps on it. Delicious to eat."
Description
Rays(Binomial Name: Urobatis jamaicensis) are underwater animals. The Yellow Ray is yellow in color.
As of current, you are unable to feed the rays, and they drop 1 Raw Fish when killed.
Rays are hostile, especially when you step on them. They have the ability to dig into the bottom of the lakes, making them almost invisible:

Apperance Biome
Yellow Rays are found in sandy lakes
Uses
Rays can be hunted for fish, so they are a food source. The only downside is that they are hard to see when the dig into the lake beds.
Yellow Ray can be spawned in Creative Gamemode using a Spawner Egg.
NOTE: For Brown Ray, click HERE.