Octo knew what it was actually for!
I was able to seal all the holes of the ball, so it filled with water as I put it into the tank. Octo went inside curious, and I slowly closed the lid with the grabber. Octo started changing to bergundy colors with white stripes, but then Octo calmed down. So I slowly took the ball out of the tank, and put it gently on the kitchen floor. As Octo shot up and stuck on the top, the ball would slowly role down... I guess Octo liked the fact that the ball moved when Octo did it. I walked a little closer, and Octo would somehow stick on top of a certain point of the inside of the top of the ball, so that it would roll a little further from me. I had to corner the ball so it would hit the wall, and that's when I grabbed it slowly (once Octo inked when I grabbed the ball with force), and put it back into the tank, and turned the lid. Octo was smart enough to push the lid out. For some reason, I noticed Octo get bigger faster, as I repeated this exercising technique for once a week... until Octo died getting out of the tank. I guess Octo was looking for the Octoball to play in.
flipflop_2k
... he looks a bit stressed. 
