"What is roof moss?" Good question. There's a house I see regularly as I walk which has been empty for several months after being sold. You can see the garage on the left.

The garage has a healthy crop of moss on its roof.

I took along a shovel and a short laddder which helped me reach the garage roof and snaffle a sample of the moss.

This, ladies and gentlemen, is roof moss.

I confess it's no different from any other moss. It just came from a roof.

As an acknowledgement that's there's more to spring than moss, I also snaffled a twig from the cherry tree right next to the garage.