Xylodon 'Schizopora group'

The fruitbody grows flat against its woody substrate. The fruitbody develops on the lower surface of its woody host and is white to creamy/yellowish or ochraceous. The exposed surface is composed of irregular pores, often with maze-like areas. Each pore is the mouth of a short, vertical tube that extends back towards the wood. The pores are large and easily seen with the naked eye and the edges of the pores are usually rough or uneven  

You see  the pored/maze appearance best when (1) a fruitbody grows on say the the lower side of a horizontal log and (2) you look at right angles to that horizontal fruitbody so that you are aligned with the vertical tubes. When a fruitbody grows on the lower surface of a sloping log then you have to position yourself very carefully to see the pored/maze appearance. Otherwise, those vertical tubes look like irregularly arranged teeth or plates.  

The fruitbodies may extend over a large area.

For some time these fungi were placed in the genus Schizopora (and often identified as Schizopora paradoxa, though Schizopora flavipora and Schizopora radula were also frequent) but those species have now all been assigned to Xylodon. You find several growth forms in that genus and identification to species often requires study of a specimen. 'Schizopora group' is a convenient way to differentiate the irregularly pored Xylodons from the other species of the genus.

Look-alikes

There are other genera of 'flat' fungi that have irregular pores but in general their fruitbodies are rarely as thick or as extensive as those of the 'Schizopora group', or they have small pores. The best look-alike candidates are probably some species of Antrodia, Ceriporia and Ceriporiopsis.