I would call a realtor or home inspector and see if they know.

Pull the bars, whittle a plug, glue and drive it in the hole, cut it off flush and forget about it.

Lovely house!

I would want to solve the mystery. I am like the OP - too much intellectual curiosity to just forget about it.

Take a photo when you get into the house and come back and post again.

"Never noticed them"????? Hard to believe.

"Never noticed them." An answer like that begs further investigation. Let the police have a look.

A picture would be nice ...

Sounds like a grounding rod for an antique radio's antenna, used in rooms where there was no easy access to a pipe to clamp the ground wire to.

OR (cue the spooky music) used where an external antenna or ground wire would attract unwanted attention ... spies used them.

Wow man! Like far out! I mean uh er you know like (wow) crawl unner da house?

"I would call a realtor or home inspector and see if they know."

We've asked our Realtor and handyman, no luck.

How about the previous owner.

Water valves?

Gas valves?

Gas valves?

They're not valves, they don't appear in any way attached to anything, just stuck thru the holes in the floor. I think they're made out of bent rebar and the holes are square.

I do intend to pull them out and cap the holes, but I want to make sure there's no function I'm unaware of (and I'm admittedly in the realm of I don't know what I don't know). I'll keep searching and post pictures when I can, but it may be a couple of weeks.

I thought perhaps they were handles that control valves under the house. It would be a handy thing come to think of it. I have a crawlspace that is not very crawlable. Really, I'd have to go to the curb and turn off the water to the house if a pipe burst, or if a faucet washer needed changing.

Maybe someone was trying to figure out their bearings when they were crawling under the house and these were markers for where they were in relation to the rooms.

"Maybe someone was trying to figure out their bearings when they were crawling under the house and these were markers for where they were in relation to the rooms."

Hmmm... That might be. We might just need to take the under the house tour. ("We" might be my husband.")

"and the holes are square"

That's really odd. Kind of tough to push square holes thru.

Maybe there was a safe or strong box, and somehow it was secured to the floor with them? Wonder if there's another part that clamps onto them lying in the crawlspace.

I am more concerned by the fact that you pull up the bar and it having moist soil. Maybe it is because I live in California but I have been told there should be nothing moist under the house.

A decent ground rod for radio use should be driven into the ground, not merely sitting on top. So that's out.

Can't imagine why something that large with a hole to match would be used as a locator when they were crawling around, altho the idea itself is a good one. And who would bother making a square hole instead of just drilling a round one?

Possibly there were these square holes for some other reason, and someone had some handy pieces of scrap metal to plug them with...

Or, they were pokers to chase off varmints from under the house? LOL

Sounds like a vent system for the crawl, or maybe a pipes from a heating system.