hi elcaro
looks to me that there is no pic

elcaro, if you don't have a photo, can you describe the leaves -- threadlike, flat, size, etc.?

Did it ever bloom? Color, size, etc.

Could it have been a moss? Yes/no/maybe?

Without a picture pretty much impossible - but check out Soleirolia soleirolii, Mind-your-own-business. That would be a typical inhabitant for such a situation.

Thanks floral you have nailed it. Soleirolia soleirolii it is.

Watch it carefully - you can end up with it everywhere as every tiny morsel can root.

Watch it carefully - you can end up with it everywhere as every tiny morsel can root.

I don't know about your state but some class it as an environmental weed.

Here is a link that might be useful: Australian weed