Small blue beads/pellets in compost?

So a few days ago I spread a good amount of the Miracle-Gro Peat-Free Compost in my garden. I was having a little look round earlier and I noticed quite a few very small, round, bright blue/turquoise beads/pellets all around where I spread the compost. I have tried to look online and the answer seems to be either fertiliser or slug pellets. I am a bit annoyed because even though I loathe slugs and would be kind of happy if some of them were to disappear, I am trying to do everything in as naturally / environmentally friendly way in my garden. Does anyone know what these blue things are? Is the solution to go organic? The only reason I don’t compost myself is because I live in London so both space and rats are an issue.