I had two avatars during my membership at ZooChat that lasted more than a couple days.
For most of my membership, it was an image of an Allosaurus display that was in Chicago in a temporary exhibition. It was not intended to be significant, I simply selected it because I wanted my avatar to be a photograph but have a rule against uploading images of my face and did not feel most of my zoo photographs were good choices; I wanted something a little more distinctive anyway. This turned out to be the right call, as my zoo photographs did not make good avatars later either, and my photos were garbage quality anyhow.
My more recent avatar had been a screenshot of an African Elephant from Zoo Tycoon 2, meant to signify my love of the games, that particular animal, and my relatively light-hearted nature. It was a very accurate choice for indicating my personality and interests but it was also a choice that felt very out of place in the context of the wider community.
It's been fun.
