Fuligo septica

Scientific name:  Fuligo septica (L.) Wigg.
Derivation of name:  
Synonyms:  
Common name(s):  Scrambled-egg slime.
Phylum:  Myxomycota
Order:   Physarales
Family:   Physaraceae
Occurrence on wood substrate:  Occurring as slimy to crust-
like sheets or cushion-like iregular masses on stumps, logs, living
plants, and wood mulches in landscapes; May through October. 
Dimensions: Masses are 2.5 to 20 cm long, almost as wide,
and 1-3 cm thick.   
Description: This slime mold first appears as a white to yellow
slimy mass with dimensions as given. The "flesh" transforms into
a crusty, cake-like mass of darker and variable color. The brittle
crust easily breaks away to reveal a dull-black spore mass.       
Edibility: Inedible.  
Comments: Although many slime mold species fruit on wood
they do not form a penetrating and absorptive mass of hyphae in
the wood substrate. Rather, slime molds form structures called
plasmodia which are naked (i.e., without cell walls) masses of
protoplasm which can move and engulf particles of food in an
amoeboid manner. Slime mold plasmodia creep about over the
surfaces of materials, engulfing bacteria, spores of fungi and
plants, protozoa, and particles of nonliving organic matter. At
some point, plasmodia convert into spore-bearing structures.
In Fuligo, the plasmodium converts into a cushion-shaped
mass of spores enclosed by an outer wall called a peridium.
This structure is called an aethalium (plural: aethalia). Fuligo
septica produces the largest spore-producing structure of
any known slime mold.

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Figure 1. In this scene, the plasmodium of scrambled-egg
slime has creeped all over this stump and even a polypore
fungus. Photo © William Roody.

Figure 2. A small plasmodium covering pieces of bark mulch.

Figure 3. This plasmodium on bark mulch is moving in an
upward direction in this view.

Figure 4. The plasmodium often spreads out in a fan-shaped
pattern over the supporting material.

Figure 5. Here, a very large yellowish plasmodium
has converted to a very large aethalium, the
spore-bearing stage.

Figure 6. A closer view of the slime mold in Figure 4. Note
the darker and varying colors of the outer peridium.

Figure 7. In the spore-bearing stage, slime molds are dry
and brittle. Breaking open the peridium exposes millions of
dry, dusty spores.