The block explorer of the steem blockchain is steemd.com created by @roadscape, where anyone can see activities performed by a steemian just by putting the username after the url. 

Example: for my username it will be https://steemd.com/@rituparnaghosh

steemd.com uses unique images of robots for every username powered by robohash.org, so you basically create an unique robot image when you sign up with steemit.

Robohash website states their service as:   

 Robohash is a easy web service that makes it easy to provide unique, robot/alien/monster/whatever images for any text.
Put in any text, such as IP address, email, filename, userid, or whatever else you like, and get back a pretty image for your site.  

Share your Robohash character in the comments.

To do so copy the link below and paste it on the address bar of your browser by replacing USERNAME with your real username. for me it would be

https://robohash.org/rituparnaghosh.png (donot put @ before your username)

Copy this-> https://robohash.org/USERNAME.png  (Replace USERNAME with you username)

My Robohash Character