Aron Moscona was one of the reasons that I became a biologist (and all neuroscientists really are biologists). I was at the MBL in Woods Hole in the late 1970’s and was taking an invertebrate zoology course through the Boston University Marine Program. The professor, the late Arthur Humes, led us through a combined field and laboratory intellectual exploration of the field that was like nothing I had experienced at college during my undergraduate years. At the end of the course, we had to devise our own experiment and mine was based on a basic finding of Moscona’s: namely that closely related cells of different species (in my case two different species of the sponge Microciona) when disassociated through cheese cloth, would somehow find their own kind to re-aggregate with. The basis for this self-self interaction turned out to be Moscona’s major discovery: cathedrins. This basic self-self cellular recognition turns out to be crucial throughout biology and Moscona’s early work during the 1950’s and 1960’s turned cell biology into a molecular-based science. We’ll miss him.