How'd this wildstock drown in such a small space?

[scrufola]

Creatures falling through 1/2 block wide gaps

We all know that the player character can walk over ½ block wide gaps and this allows for some really cool chisel possibilities. But thats not true for creatures right now. They fall through ½ block wide gaps. Just wanted to check if thats intentional. This is the top of my workshop. The skylight is at ground level on the mountain top and creatures fall through it on a regular basis. [20180930121800_1] [20181001155355_1]

Creatures have smaller hit boxes.