What limits an octopus from squeezing through a hole

[wolfw28]

I have heard two different storys of what prevents an octopus from squeezing through a whole seam most of the online community says it it break I have heard from other it the size of it brain witch cant be compressed. Hoping I could find the answer here.

 

[tonmo]

The beak is what I've understood to be the only thing that's really uncompromising. Our own @ceph (Dr. James Wood) ran a test on this years ago:

 

[Hadla]

Yeah I think it’s the beak which is said to be about the size of their eyes. That’s the only hard part of their bodies