Orange webbing ?

[Leedowlrods]

I'm house sitting for a friend, his (now dead) euphillia skeleton now has an orange coloured webbing over it.
It has exit/entry hole in it.
Sorry for bad pic,

 

[Ingy]

looks like a sponge. That and some bubble algae. Eek

 

[Leedowlrods]

Between me and you, it's a very dark and gloomy tank, think I'm gonna encourage him to get more lights.
Haven't seen the emerald crab yet but theres time yet as I'm here for a week.
Will be checking all levels tomorrow