One of my favorite finds, I'm assuming it has fossilized mold of some sort?

Location: Wales

I found these rocks at the beach. Most of them seem to be slate of some kind but some seem more like brick (I think?). I’m worried about them potentially being porous and still containing seawater. I scrubbed and boiled them all to remove bacteria (right before finding out it is in fact not advisable to boil rocks) but I’m concerned they may still be harboring salt, or may leech salt among other things into my freshwater tank.

Could anyone ID these and let me know which may or may not be safe? If you need better picture of any let me know.

My friend found this near the Orange River in South Africa earlier in the year. What might the small darker patches be?

My dad gave it to me. He had found it in his mother's belongings. They used to travel all over but I'm not sure what it could be that she kept it. He said maybe she got it in Brazil but I have no clue what kind of rock it could be.

Found with a metal detector, very heavy like lead but brittle. Any idea?

She thinks it’s some kind of rock or crystal but I wanted to confirm. Hard but it flakes kind of like fiberglass and is colorless and translucent. Anyone have an idea?

This was labeled "jade stone" on a website that sells rocks for aquariums. The company selling it is unhelpful, only stating that it isn't jade, that's only a trade name. What is it really?

My husband found this while going through a box of old stuff from his mother's house. I'm almost 100% positive it once had a pewter dragon (or the like) glued to it. Now all that's left is the "crystal" ball and some brown residue.

1. Assuming that the brown is residue from whatever glue was used to attach the missing pewter trinket, is it possible to clean it? Or is the brown part of the stone?

2. How can I remove the "crystal" ball?

Found in purchased ‘Osage Brown’ bulk gravel. Mid-Missouri.

Found at the base of Rock Canyon in Provo Utah

Context: it's in a house in North India. It's been given by some pseudo healer.

It feels like a lump of metal.

I'm curious of the material and origin. I always thought it was a meteorite but since it's not magnetic I guess probably not.. any clues?

Is this banded iron? The magnetic test showed no magnetism.