While retaining the basic external characteristics of the 55 - year - old classic, this pickup now features many modern options and upgrades. (barrett-jackson.com)
Some animal species look so alike that external characteristics do not provide sufficient information about whether they belong to the same species or not. (sciencedaily.com)
Until this imaging, tardigrades were classified using external characteristics, leaving many questions unanswered. (discovermagazine.com)