Not only does the Duck Creek formation have ammonites, it has some echinoids as well. I found a couple of nicely inflated specimens of the irregular echinoid Macraster. I sent pictures of my find to a friend in Texas, who is familiar with the Duck Creek formation, and he said they could be either M. elegans or M. washitae. Macraster has a suboval shaped test with a sub rectangular cross section. The adapical surface has the typical five arm imprint of the ambulacra which is where the feet of the animal would have extended from. There is a small oval shaped opening in the posterior of the test called the periproct which is where the anus of the animal would have been. On the underside, or adoral surface, is the opening for the animals mouth called the peristome.
When I was a kid I called echinoids with this shape "sea biscuits".
Specimen #1 is a little water worn.
Specimen #2 is missing some of the test on the adoral surface
The only other Echinoid evidence that I found was this isolated piece from a regular echinoid.
The above specimens come from the Duck Creek formation which is Cretaceous (Albian stage) in age.