You can ride Sea turtles in the same manner as a pig. You cannot control it.If you do kill it it should drop a shell!

Sea turtles can be hatched from eggs found near adult sea turtles.  To hatch, place the eggs ON LAND near a body of water.  The eggs should only take a few seconds to hatch and will start rocking back and forth.  When the baby turtle hatches out, it will find the nearest body of water by itself.