common brown octopus

I bought this shark egg at a local fish store I go to and they had the usual Brown Banded Bamboo shark egg, but next to it was this egg and it's about double the size, same color, same transparency (so almost impossible to see through unless you have a light), so of course the type of person I...

So I came across this the other day... Neat looking little fellow. Got me to thinking about a tank for one. Maybe a 20 long set up like a peninsula. Epoxy a sturdy rock structure together and maybe some clear glass bottles/jars. Set it up in living room or dining room so he can watch everything...