What is this hole we found under the carpet?

We were having a new carpet fitted today and when the workmen pulled up the old one, they found this hole. Does anyone have any ideas as to what it is? The guys theorised on it being someone’s secret hiding place for…who knows what. The house is old - built in the late 1800s. It has a basement but the room below this one is bricked up so I can’t check if it’s connected to anything down there. It’s not too deep, maybe about 30-50cm? I didn’t have much of a chance to investigate it because the guys had to cover it up so they could put the new carpet in.

What is this brown glass thing found on Caribbean beach? Adjacent item for size reference

4ft tower-like shelving with wood and wire slots. Only six inches across. No brand markings TIA

What is this marker on the highway?

White round plastic disc that says “for travel use only”

It says “for travel use only” and “do not discard”

Kinda stiff, white, gauzy-ish(?) roll found in sewing box from estate sale

Title explains it- it's a roll of something white, it looks kinda gauzy but not quite. It feels stiff but it can't really hold itself up. I'm assuming it's something sewing-related but I'm self-taught and have never seen this before. It didn't have any packaging with it. Thank you!

Diamond shaped plastic with a thin metal rod. It has wy logo and to bumps on either side for grip? Looks to be a locking or reset device. It was found on my bedroom floor and I have no idea where it came from.

small semicircular rubber object stored along with jewellery

regular sized safety pin for size comparison. the other side is marginally larger than the camera facing half and is missing the two oval indents.

Why is this hole in my garage?

House built in 1982. Central -ish Florida. 36" × 26" and 26" deep. The bottom is our native soil(sandy). Can anyone tell me what the purpose for this is? Very curious. Currently using it for random storage.

Aluminum frame with netting, about 12 inches square.

Hi, this table was advertised with no description, measurements or any other photos. All 4 sides appear to fold upwards for some reason, the hinges retract down into the legs. It seems to be made from good quality wood and is for indoor use.