I have a layer comprised of about 500,000+ simplified polygons that resulted from converting raster cells to polygons with raster cell values assigned to them. When I select the resultant polygons by attributes (say, those that have values above a certain threshold), I end up with a bunch of contiguous spatial clusters. My goal is to create an outer shell boundary circumscribing those clusters, which can be achieved using the Dissolve Tool in ArcMap.
The problematic twist here is that I want to be able to identify these clusters of dozens of small polygons individually after dissolution into "island" shapes. How would I go about it?