I'm trying to complete the Field Research bundle of the community centre and I'm only missing the Nautilus Shell. I've gotten two Nautilus Shells before, but both times, it wasn't the "right" Nautilus Shell apparently as I couldn't put it in the bundle. I can't seem to find the right one anywhere. I've tried looking online, but I only can find a SINGLE reference to Nautilus Shell instead of multiple, which confuses me.
I'll add some images for clarification
I can't seem to find any info on the one I need, and it makes it difficult to search as they have the same name. Is the one I need also an artifact? Where is it found?