whilst caving yesterday we came across an old inlet which had some type of purple algae on the wall. it was away from the mainstreamway and didn't appear that water had risen up the wall to where the fungus/algae was. It glowed a violet colour and gave a speckled coating.The intensity of the colour seemed to increase as more light was focused on it. It really was an unusual find and we could not decide what it was. The consensus was that it was some type of algae that didn't need light to grow but reacted to light.it looked organic - certainly not mineral.We were about 300m from the entrance but perhaps only 5-10m below the surface.Anybody got any ideas what this may be - it has us all talking as some of the guys have been going underground for 40 years and had never seen anything like this.thanks

The Matienzo Caves site has a hole (Treasure Cave) with a documented purple growth.
http://www.geography.lancs.ac.uk/Matienzo/descrip/1053.htm
Look at the underground photos - the purple algae will jump out at you.

. . . but are they "algae"?

Wow, some of my pics 

The purple growths were in the twilight zone, not deep underground. They were on the walls in picture C3 which was taken looking out of the entrance.

Bren,

I would suggest contacting Diana Northup through http://www.caveslime.org/, if she doesn't know what it is she will certainly want to find out!

Ed

Thanks for the replies.my pc blew up last sunday n i only just gotit back.the oictures were nothing like what we saw.it was more like a surface coating as appose to a growth.but thanks for the input - will try to get a photo to help,

Which cave was it in, Bren?

will PM you