We're currently working on enabling showing "ignored" values in Discover (elastic/kibana#115040). Those are values that have been injected into Elasticsearch, but were there ignored, e.g. because they were too long or were malformed. They can thus be shown, but not being filtered/searched for. We currently use the general alerting icon for indicating this:

I think it would be nice if we would have a slightly more specific icon, since it's not really a warning, just a hint to the user why those values might not be searchable (we're not yet decided on if that text will stay yellow or will become subdued).

I was thinking along the lines of having maybe some "striked through magnifier glass" or something along those lines, but am happy for any Design input on this.