Hi.
This purple layer of what seemed to be some clacium build up or maybe some type of coraline appeared on a rock that I got years ago after the zoos that were covering it were eaten by some of my fish. i directed a powerhead on it and got all what was covering it and it turned out to be pinkish in colour and very thin. would brake off at its edges if manipulated to show a thin slice with whitish internal aspect.
I traveled for 2.5 years and was taking very minimal care of the tank when I was back and noticed at one stage it started growing. it ougrew the rosk and formed an edge going out. recently I noticed that it's shedding it's upper layer. Its not a leather and is not soft for sure. any idea on whtat this is? it's a bit more purple than how it looks in the picture and these pics were taking when it was "shedding" its outer layer.
Thanks for any info