It's the translucent shadows that made this so much fun to paint. The coloring ties the objects together, but the elipses repeated throughout also give them a relationship.
The items in the lower right corner are weathered glass bottle stoppers. I found them on the beach of David's Island which is not far from where I live. The Island has been abandoned for many years, but had a military base and housing there late enough to have an underground missle storage area. Because of the population that was once there, it is a gold mine of old glass bottles, pottery and more.
Unfortunately, (or not, depending upon your point of view), the Island has been off limits for several years now as the town it belongs to has decided to develop it into a park area. Until that work is done, no one is allowed on the Island.