Just go read the series here, I’ll pick out my favorite images and comment.
Here’s how I’d handle it. I’d explain that once you die, your body begins to decompose. It decomposes because those formerly helpful flora in your gut decide to start eating you.
Once that starts there are all sorts of interesting gases that get created that attract insects and vermin. They’ll munch on the flesh remaining on the outside for as long as it takes to strip your skin, fat and muscle, then your internal organs which by now are bloated.
Eventually your viscera will liquify and all that will be left is the calcified skeleton.
To sum it up, you rot, or fester as the case may be. Until such time that all that’s left is bones.
All because of fauna, flora, and insectoid.
Aren’t you glad you know that now? It’s why embalming drains out the fluids, and stuffs the body full of preservative in the form of formaldehyde.
It delays the eventual festering. And your body is placed into a hermetically sealed casket and then lowered into a concrete vault. So chances are the only bacterial flora left will have to devour you over a longer period of time, with no fresh oxygen. Fun!