Follow up on white stone beads

I posted these on my finds thread lower down. I'm still not sure what they are made of despite a thorough clean. Definitely not coral or glass, some type of stone. They do look like fossil beads that were suggested but lots of them have what looks like rust patches so either they have been near something rusty or have iron oxide in the stone?.
These were two different strings of beads bought from two separate sellers,one in an antiques fair and one in a charity shop. Beads in both strings are the same size.
Thanks for looking
String 1-

String 2-

 

So they feel cold?

 

I saw tons of these in the 80s dyed different colors. No idea what the stone was.

 

Yes

 

Hi, new here!!! About the beads, I think they may be cultured pearls. I have recently come across the same type of beads. I washed and washed the beads. They had a sticky paint residue on them. Mine are a good weight like stone and are cold. They are also all the same size. Cultured pearls are grown. Natural pearls are found rarely, so that is why cultured pearls are grown. Natural pearls are expensive, cultured pearls are more affordable, and faux pearls are considered fake and are relatively cheap.

 

Pearls these aren't. I've seen lots of cultured saltwater and cultured freshwater. A few of the real ones too - all natural - but none of them were made with stone cores like this.

 

I agree, not pearls. Could be some sort of fossil coral, although not of a kind I know.

 

If thr coating washed off your pearls, leaving a cold hard stone, they were probably glass to start with, I'm afraid.

 

Likely to remain a mystery!