These are conidial fungi where the conidia form in a growing cavity in the host's tissue.
Sphaeropsidaceae are fungi with pycnidia dark colored, leathery to carbonous, stromatic or non-stromatic generally provided with a circular opening.
Zythiaceae are fungi with pycnidia as in the Sphaeropsidaceae but light colored instead of dark, and soft or waxy instead of leathery.
Leptostromataceae are fungi with hpycnidia shield-shaped or elongated, and flattened.
[1] Members of this order can produce bisnaphthyl pigments, such as Sphaerolone and dihydrosphaerolone, or 2-hydroxyjuglone.