Great Steam Turtle

TERROR OF THE SEA

"Turtle, ho!" the lookout in the crow's nest yelled down to the crew below, one arm waving wildy at what looked like a barren island rising out of the sea.
"Cut the nets!" Captain Redhill yelled to the crew of his fishing boat. "By the gods, men, cut the nets and make all sail!"

— excerpt from 'No Mercy At Sea'

Turtle, Ho! by Comfreak

Great steam turtles are sea creatures that never stop growing and never grow old. The only natural deaths they suffer are from disease, being eaten, or starvation. The latter happens when a steam turtle gets too big to catch enough prey. The only thing that eats a great steam turtle is another great steam turtle. This is a very good thing as otherwise the seas would be emptied of life as they will eat anything and everything that moves in, or on, the water. Algae blooms, schools of fish, plankton blooms attract schools of bigger things that come to eat them. It is these schools of bigger things that attract steam turtles
The biggest, and possibly the oldest, great steam turtle ever found had a shell a mile long and half a mile wide.

BEASTS OF STEAM

Turtle Steam by DeSa81

"Smoke!" the sailor called out gleefully as he sighted down his rail-llista at the enemy ship that had just disappeared in a cloud of white.
His glee turned to shock as a great green beak poked out of the cloud, gaping wide. The enemy ship foundered in that gaping beak. With a thunderous crunch, the beak closed, splintering the enemy warship in one bite.
"Turtle!" he screamed, the dread sinking his stomach down to his ankles. Other sailors echoed his scream.
"Where?" Commodore Starlake demanded.
"Away the 'llistas!" the captain yelled, not waiting for orders from the Commodore. "Clear the deck! Trim the sails! Helm full to port and catch the wind. May the gods save us, catch that wind!"

— from 'The Battle No One Won'

From their nostrils, steam turtles breathe out billowing jets of hot steam. This creates a blinding screen to slow the escape of any prey. Two pouches in its neck can hold the steam that older steam turtles are careful to not use up all at once. Young steam turtles tend to let all their steam out in one great attack until they learn to control it.
Great steam turtles do not reach breeding age until they are a hundred years old, and females then wont breed again for another hundred years. After mating, the females dive deep to the deepest parts of the oceans where there are hot sulfuric vents to lay their eggs. These eggs which are about a foot long and are incredibly tiny for such a massive creature, but they make up for it by laying hundreds of eggs.
It takes a month for the eggs to hatch. Once they hatch, the baby turtles will devour all the creatures living around their hatching vent. They have no need for air as they are able to survive on the sulfuric steam. This ability lasts only a month. After this month, they fill their neck pouches and lungs with the steam from the sulfuric vent and swim the long, long way up to the surface where they will begin breathing air for the rest of their lives.

TREASURES BENEATH THE SEAS

"I will not marry into any pod that cannot afford a turtle egg feast for our wedding! I don't care how close to the king they are. The shame, father, the shame is just too much!"

— a young merfolk maiden protesting who her father has chosen for her to marry

Steam Turtle Eggs by Viergacht

To the undersea folk, steam turtle eggs are considered a delicacy to be served for great momentous events like coronations and noble weddings. The search for the eggs, which can be tricky as vents tend to go cold and females lay only once every hundred years, can also be a means for a young royal heir to prove themselves worthy of the crown. When the rivalry for the crown gets intense, some heirs are required to hunt down a baby steam turtle. This is a deadly challenge. It's so deadly that the challenge often changes from whomever comes back with a baby steam turtle to the heir who comes back alive, successful or not, getting the crown.