We have a block driveway, and as well as moss, there is also a small
green weed that grows in the interstices between the bricks. It has
been called "mind your own business" but I don't know whether this is
correct. It looks like pondweed - very small dark green leaves. The
thing is, nothing kills this stuff. I have tried weedol and path clear
and it just shrugs them off. Does anyone know what this could be and
how to deal with it? It's not a big thing, but very annoying.

Any help most welcome. Thanks
In limine sapientiae