Answer to Case 791

Answer to the Parasite Case of the Week 791: Not a parasite; most closely resembles calendula seeds.

This was a fun case to try to figure out! Almost everyone correctly recognized that this object was not a parasite, and the history of calendula application quickly pointed many of you toward the true source. I consulted our botanist colleague, Dr. Mary Parker, who agreed that this object closely matches a calendula seed. 

Here’s a comparison image from the USDA website (top) and our current case (bottom):

Calendula, a genus in the daisy family (Asteraceae), is commonly known as marigold. Calendula-based products, especially calendula oil, are often promoted for hair growth and scalp soothing, though I wasn’t able to find supporting evidence for these claims in PubMed.

As you can see from the photo, Calendula seeds are small, curved, and ridged, making them look surprisingly similar to certain larval insect forms or even trematodes. A great reminder that context and collaboration are key in solving these “parasite mimicker” mysteries!

Thanks again to Drs. Moss and Pettengill for sharing this great case.