Upon displaying an output rmf3 file on Chimera, I am getting a number of large, radially distributed spheres as part of the model. Within the rmf3 file hierarchy, they are not part of the System or States within (meaning I can exclude these spheres from visualization by showing only "System" in the rmf3 file hierarchy panel). I wonder exactly what they mean. If anyone has experienced these before I'd appreciate any help interpreting and/or addressing this issue.