Squid's line of sight extends to another direction other than the length, width and height, perpendicular to the length, width and height, which is the fourth direction. No three-dimensional object can close it, because any closed three-dimensional object has no effect on a creature with four-dimensional consciousness, and being able to enter four-dimensional space means that you can change from three-dimensional at any time as you like, which is the main reason why squid is a four-dimensional creature.