It sounds as if it is an associative hatch.
If you enter -hatchedit at the Command prompt, HATCHEDIT displays prompts on the command line.
Select associative hatch object:
Enter hatch option [Disassociate/Style/Properties] <Properties>: Enter an option or press ENTER
NOTE You may have difficulty when trying to select a solid-fill hatch pattern because there are no visible grips or lines to click. For best results, either click the outer edges of the hatch pattern or use a crossing window selection.
Good luck
Selection of associative hatches and their boundaries depends on the setting of the PICKSTYLE system variable. To select an associative hatch without its associated boundary, set the PICKSTYLE variable to 0 or 1. To select an associative hatch with its boundary, set PICKSTYLE to 2 or 3.
PICKSTYLE variable settings
0
No group selection or associative hatch selection
1
Group selection
2
Associative hatch selection
3
Group selection and associative hatch selection
If you want to erase a boundary hatch pattern without erasing the boundary object(s) as well, set PICKSTYLE to 1 before erasing the boundary hatch.
Variable Type: Integer (Saved in drawing.)
Initial value: 1 (Controls use of group selection and associative hatch selection.)