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The elongate structures with the saw-teeth on each side remind me of graptolites. See this image from the Illinois Geological Survey: https://isgs.illinois.edu/outreach/geology-resources/graptolites. Grand Isle seems to have Ordovician formations, so that fits. My advice is to go to macrostrat.org or rockd.org and look up which formations are in that area. You can then google search the formation name + “fossils” to look up any papers that have been published, and what species have been documented.

Thank you for the shared information, it is very helpful. 😉