Growing on a carpet and up the door

[scipio]

My open compost heap has sides made from old, gloss painted doors. The section into which I throw new matter is covered by an old carpet (it stops it blowing about and the slow worms like it). I last mowed the lawn 4 days ago. I take off the carpet, mix the cittings with shredded paper and throw the carpet back over. On Sunday I took someone to see the slow worms and to my surprise the carpet was attached to the paint with this:
http://www.wildaboutbritain.co.uk/ar...dium/Size1.jpg
No only had it attached itself to the carpet and gloss paint but appeared to have mycelium attached to the grass:

I broke a piece off to examine the structure:

and here is the broken-off bit on my hand. It is quite firm and crusty.
http://www.wildaboutbritain.co.uk/ar...um/Fungus7.jpg
I expect you know what it is but I have been living here (sandy soil, birch woodland) for 30 years and have never seen anything like it before.
I'm just amazed that it can get that big in just a fer days.
Any information will be very welcome.

PS sorry about the random thumbnails, the site did not seem able to produce them in all cases.

[CapAndBracket]

Looks like the slime mould Fuligo septica.

Cheers J.P.

[scipio]

Thanks for the id of Fuligo septica.
Every picture of it on this site shows it as bright yellow whereas this is anything but that. Does it really go from nothing to a large yellow blob and then to this loaf-like state in just 4 days.
Blink and you would miss it (In fact I did!).
Thanks

[CapAndBracket]

This one appeared as yellow mass, in the photo it has a red/pink tinge to it, two days latter it was black. But yes the plasmodium is described as an acellular, multinucleate mass of protoplasm bounded by a cell membrane. In this stage of development they are virtually clear, probably more within than on the substrate so spotting them seems nigh impossible.

Cheers J.P.