u/ImpressiveSell5404

What is this piece called and what steps should I take to fix this?

This piece keeps disengaging randomly.

Thanks!

No idea of the material. Husband thinks its quartz.

We've been here only a month. It's been a whirlwind, but I am 99% sure this was not here when we moved in. It's a bathroom that's rarely used and has had only one plastic container of antibacterial soap and one glass cup on/near that area.

Could it possibly be fluoride from toothpaste residue that dripped down and settled?

Kiddos cleaned the bathroom a couple weeks ago but we didn't have any caustic cleaners.

Any ideas? I don't think this is fixable but I'd love to not make it worse.