Lobes

[Sepioteuthis]

Look at his muscles!!

If it takes a captive 6 years to reach Dume's skull size, do you think he's at least 8 or 9 years old?

I wouldn't be surprised if he's that old, but I would think it's difficult to determine that based on size. Growth rates differ after all. We may know more once your 05 CBs reach that age.
I guess for now it would be more accurate to say that he's at least 5 or 6 years old....?