Beard algae goes purple

In the continuing saga of the upgrade of my tanks, I have come across what I
believe to be a first.

Dark beard algae goes bright alien psychedelic pink/purple when dried.

To prepare my fish for the move from the old tank, Saturday I removed almost
all of the hidy holes, and cut back all of the plants, to facilitate
capturing them next week.

I've had a rampant growth of black beard algae for a couple of months now,
but because I knew I was moving didn't get rid of it with the greatest of
vigour, I removed all the objects from the tank all covered in algae and
dumped them outside. I went back to the old house yesterday to feed the
fish, and the dried algae outside has gone an amazing purple colour. Has
anyone else seen this?

Cheers

A