Fused scales?

[Paleosuchus]

I have seen this many times, scales being whats looks to be, fused together into one giant scale. Most of the individuals i have that have this is unnoticable, you have to really look to see this. But my adult ball python has a "giant scale" of about 5-6 scales joined together. Just wandering what causes this, and/or if it is just a simply deformity within just how the scales form? Thanks, jason