The surface colouration is initially white but quickly becomes black but may also exhibit pink or orange on the surface depending on the growth medium and species.
The reverse is also dark brown or black
Stachybotrys has hyphae which are septate and hyaline when young but may darken with maturity.
Conidiophores may also be hyaline or may develop an olivaceous or dark pigmentation. The conidiophores may be septate, simple or branched. Conidiophores may show a rough-wall texture, particularly at the upper part, near the phialides.
Phialides (9-14 µm in length) may be hyaline, olivaceous to black in colour. They are ellipsoidal in shape and form in groups of 3 to 10 at the apex of the conidiophore
Phialides produce conidia singly and successively into a slime droplet that covers the phialides.
The conidia are 7 to 12 by 4 to 6 µm, black, unicellular, ellipsoidal in shape and smooth to rough-walled. Conidia are borne in slimy masses at the apices of the phialides.