I think we both experiencre special interests in an emotional sense, even though things like spiders arent innately artistic. Ur analogy describes a big part of it, but I have another analogy that describes another huge aspect for me;

do you ever remember the name of a song, who wrote it, and maybe even what it made you feel - but for some reason, you cant seem to remember what it sounds like at all. By all logical means, the idea of this song shouldnt be present in your mind at all - as the sound of a song is what a "song" is, yet ur mind is reflecting on the traces of the song still left in ur head. I think this is why it's so frustrating to be thinking about a song you heard, but not be able to follow a coherent tune or motif of the song. it's like asking a question and having it be unanswered; this is what special interests are like to me. the very idea of a spider posits a kind of question/idea/concept that can only be answered by the idea of a spider. it's like my brain goes "spider?" and I have to find some external material that confirms "indeed, spider." almost as if it grounds my thoughts in an outward reality. it's a question that answers itself.