I have a problem with this closed polysurface

It says that the object is a closed solid but visibly it has openings and I have trouble fixing it.

part 2 Grivna piramidi.3dm (888.3 KB)

is a visualization problem because that surface has some weird edges there:

if you extract those tini surfaces and the big one and run Cap, it works ok

Thanks a lot!
I tried the same thing with this similar object, but this time it did’nt work.
grivna piramidi.3dm (1.1 MB)

you have the same situation in both ends.

When i remove the small surf aces and cap everything it still stays as an open polysurface
grivna piramidi 1.3dm (1.0 MB)

you have some bad trims and some small disjointed surfaces.

simple fixes… extract, untrim, merge edges, retrim, etc…