Answer to the Parasite Case of the Week 643: Not a parasite; plant material.
As mentioned by Idzi, Bernardino, and Phil G-J, this beautiful structure is a peltate trichome, possibly from an olive (Olea) leaf. Bernardino Rocha provided a great link to this open access article and the photos look just like what we are seeing.
To obtain further insight, I contacted our knowledgeable botanist reader, Dr. Mary Parker, and was pleased to hear that she agrees with our assessment! She commented that this structure is definitely a peltate trichome and could quite possibly be from the lower epidermis of a leaf of an olive tree. The trichome could have been a contaminant of olives or olive products (e.g., preserved olives, tapenade, unfiltered olive oil) and thus ingested to end up in our specimen. She also mentioned that herbs like mint have glandular peltate hairs on their leaves, but that there are usually fewer of the radiating head cells; therefore, Olea is a more likely source. She provided this striking photo of the lower epidermis of an ash leaf with a trichome. You can also see the guard cells of the epidermis - something we have featured before on this blog (Case of the Week 534 and answer)