Roddenberry's official explaination was They always looked like that. We just didn't have the budjet in the 1960's to show them properly.¶ This is one case where I prefer the Doylist explaination.

Stands of staghorn coral were bleaching white.

In the United States, peramivir is not likely to be used for routine treatment of seasonal or pandemic flu, partly because most primary-care physicians do not administer intravenous infusions.

If you had been there, you'd've laughed your head off.