I couldn't miss the chance to practice my drawing!
The Boss Turtle is an enemy from Final Fantasy Crystal Chronicles: Ring of Fates.
It fights identical to the Spin Spine and should be treated as such, despite it having increased stats and needing the proper Arm Boost ability to pick it up and throw it. It is fought in the area where the Crystal is fought, and is flanked by two Spin Spines. Upon defeat, it will drop the same spoils as the Crystal.
It is easily identified by its increased size compared to the other enemies in the area.