We might even call it "favicon", for the fun of it… :-)
An identicon is a hash value represented as an icon. "facebook.com", for instance, may hash to a red image with a yellow line through it. While you wouldn't remember the icon initially, over time you would – or at least your subconsious would. If you ever visisted a fake-Facebook, you'd immediately notice that something was wrong if the icon suddenly was green with a blue dot in it, for instance.
However, teach users to read domain names! If users do not grasp the general concept, e.g., if the supposed identity is just "example" (possibly with some decoration considered insignificant) and not "example.com", how are they supposed to survive? Domains have been around for more than a quarter of a century, the Internet is actually part of our lives… There is no excuse, and there is no sense in pretending that there was no harm in not understanding the basics. That said, there are real ambiguities that have to be addressed.
FFS, if users cant see that somedomainname.com is different than somedomanname.com how does a randomized image of the domain name based on a hash solve this.