I downloaded a prt file from here that I'm using in an assembly I plan to 3D print: Penguin PERCY - SOLIDWORKS - 3D CAD model - GrabCAD

I did scale it, but that shouldn't matter for this question. I did quite a bit of SolidWorks freshman and sophomore year,  but haven't touched in in a couple years so I'm pretty rusty.

Basically, to 3D print this at the size I want it, it needs to be solid. When I open the model, the visuals show something funky going on with the feet (they look hollow). Additionally, when I go to mass properties it says it has 0 volume and 0 mass. BUT, when I extrude a cylindrical cut through various parts of the model, it seems to show that the model is completely solid.

Basically, I'd just like to know what's going on with this model (is it solid, why do the feet look like they have holes?) and how to figure out the actual volume of material.

Thank you for your time!

Attached is the actual PRT file (scaled) that I'm using.