Unknown item shown in rqt_graph

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In my rqt_graph shown below, the namespace path_modification has an oval titled color in the namespace. What is this?

I've looked at rostopic list and it's neither a topic nor a service running on the network. I've googled around, but I can only find information about the display color of a node in rqt_graph, not an item titled "color" in rqt_graph.

rosnode info path_modification returns:

Node [/path_modification]
Publications: 
 * /rosout [rosgraph_msgs/Log]

Subscriptions: None

Services: 
 * /path_modification
 * /path_modification/get_loggers
 * /path_modification/set_logger_level

contacting node http://127.0.0.1:44616/ ...
Pid: 11250
Connections:
 * topic: /rosout
    * to: /rosout
    * direction: outbound
    * transport: TCPROS

I don't see anything related to "color" at all in that output. I don't think rqt_graph shows rosparams, but I checked rosparam list and I don't see "color" in there either. The output of rosnode list is:

/path_modification
/ramp_planner
/ramp_sensing
/rosout
/trajectory_evaluation
/trajectory_generator
/trajectory_view

So it doesn't seem to be a node either. If anyone knows what this is, please let me know. Any help is appreciated.