Corals are not terribly common in the section of the Kalkberg formation that I have collected and most of what I have found are small examples. Such is the case with Favosites heldergeriae as seen in these two examples that are about the size of a US quarter.
This first specimen has a small mound starting in the center and is spreading out.
When it is flipped over you can see the epitheca which is slightly wrinkled. The most notable feature of the ventral side of this fossil is the odd checkerboard pattern. Obviously the coral settled upon something and then recorded a negative impression of the surface as it grew.
I did a little more digging and found that Hall lists Recepticulites infundibuliformis (=Recepticulites monticulatis) in Paleontology of NY, Vol 6, pg 289, pl. XXIV fig. 3-11 as coming from the lower Helderberg. Also I found a paper by John W. Wells in the Journal of Paleontology Vol. 30, No. 3 (May, 1956), pp. 747-748 that discusses a Recepticulites found in Upper Devonian strata of NY near Cornell: http://www.jstor.org/discover/10.2307/1300307
So the coral colonized a hard surface that happened to be part of a Recepticulite (expired?) colony and preserved an impression of the surface. That is pretty cool in my book!
Here is a second, smaller specimen of F. helderbergiae but, alas, the ventral surface is not well exposed so I can't see if there is an impression of what it colonized on the epitheca.
Finally, I have a larger example to show you. I think it is a F. helderbergiae but it could also be F. conicus which is also known from the Kalkberg formation.
All the above specimens come from the Devonian aged (Lockhovian to Pragian stage) Kalkberg formation. I found them in a roadcut near Schoharie, NY.