These are fun to play with.

Flatten only one side, Write something clever with a waterproof marker on the back.
Perhaps the date and what it is. Just not a grit number.

Find a scrap of mild steel to worry the surface with. You can take a cut off of bar steel
or square tube steel and common sand to speed the surface tidy process.
I wore out a bit of wet sidewalk to get mine flat enough for a visit to sandpaper then a DMT.
Not many are fine enough to shave off but as you discovered they are nice for
touching up a lot of kitchen knives.

They also make nice "stands" for other hones to get them up off the counter.
Use some newspaper as the first layer to catch the grit then the CNAT then a no slip mat and
then your favorite hone. Damp newsprint paper is non slip catches water and grit.
Do watch out for ink transfer to a fancy countertop that we do not want grit from
honing to scratch.

have fun.