Which drug these school kids used ? : CafeDread | Torhoo darknet markets

I was a prefect and in our school some children younger than me like 8th grade 9 grade students , our school sir's noticed children are using a drug it's black color they keep it under tongue i guess ,
so what we do is randomly decide and check student bags and tongue and i saw too kids are using drug ,

and ofc i only use psychedelics nothing else but i'm curious to know what drug is it ?
in our area dark web thing is not that popular at that time i think few months before silk road bust or after ....
if u ask what is dark web they'll say it's a site where red rooms etc things happen they see it as a criminals place
and that's how many youtubers explained about dark web and there are still sites
not a way to use internet anonymously ....