this file is probably in esri grid format. Be sure have both the dataset and info folders. Catalog will only recognize data that is in the proper structure to be read; to see what's actually in the folder you need to use Windows Explorer.
ArcGIS Help (10.2, 10.2.1, and 10.2.2): Esri Grid format
workspace_folder
\
mygrid
\
xxx.adf
prj.adf
...
\
info
\
arc.dr9
xxxx.dat
xxxx.nit
...