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That is odd that it looks unfinished in the hole. I would expect a base of some sort. I would put some kind of cleaner like bleach in there and suck it out until it is clean down there and figure out what piece is missing or why not finished. That foam should be sealed. If my project I would drill out as much foam as I could and then dry it out and then pour in new foam and drill for a new base then seal that foam with epoxy.

Foam looks cracked and water logged. Once you pull out old foam then maybe the water extrusion will be more obvious.
Archie