There's an old saying — truth is stranger than fiction. When we take inspiration from the world around us, we add creative depth to our worlds, because reality lets us be braver and gives us a place to start. For this edition of the newsletter, I wanted to take a look at how I do creature creation for my stories. It's important to me to riff off of little-known and unique animals, because it's a great way to help people learn more about the amazing world we live in. When coming up with the original idea for the people of Eheu Isle, I was actually inspired by lore about elves. Specifically the idea that faerie has an allergy to iron. It's a common motif in Irish mythology, perhaps related to an oral tradition about the impact of iron weapons on the indigenous people — or perhaps not. Most blood, which is vital to the survival of most species, is iron-based. The more I thought about elves and faeries being allergic to iron, the more I wondered what _their_ blood looked like. In her article about [the properties of vampire blood](https://www.ithilear.com/2017/09/the-powerful-properties-of-vampire-blood.html), Beth Alvarez discusses how the 1991 novel *The Vampire Diaries* is the origin of the idea that vampire blood has healing properties. But how plausible is this? More plausible than I thought, honestly. Horseshoe crabs, along with some other arthropods mollusks and crustaceans, are among the few animals on Earth who have hemocyanin instead of hemoglobin in their blood. Hemocyanin is one of the strongest known antigens. Antigens are able to stimulate strong immune responses, so hemocyanin is often harvested from horseshoe crabs to help vaccine development. Put simply, the the blood of a horseshoe crab can help humans heal. Hemocyanin is comprised of a [copper base](https://animals.mom.com/relatives-horseshoe-crabs-5041.html); instead of instead of the more typical iron-based blood that humans and most other terrestrial animals have. This is just one more way the humble horseshoe crab is a ripe source of inspiration for inventing fantasy species, especially those who [can be harmed by iron](https://tvtropes.org/pmwiki/pmwiki.php/Main/ColdIron) — fairies and elves being the most common example. Creatures with copper-based blood use the protein hemocyanin instead of hemoglobin to carry oxygen to their cells. Unlike hemoglobin, which is typically blue but turns red in the presence of oxygen, hemocyanin is clear until exposed to the air — then it turns blue. Creatures modeled on horseshoe crabs would therefore bleed blue instead of red. If humanoid, their skin tones — particularly while flushed — will be bluish instead of pinkish. Most hemocyanins are inefficient compared to hemoglobin, efficient as hemoglobin at transporting oxygen per amount of blood. The exception to this is in a cold, high-pressure environment. Consider species that evolved in environments with low oxygen or high gravity (or both) — places like the ocean deeps, or high mountains, or even space. Examples include the ["genies" in the Honor Harrington universe](https://en.everybodywiki.com/List_of_alien_species_in_the_Honorverse) or the [Outsiders of Larry Niven's Known Space universe](https://larryniven.fandom.com/wiki/Outsider). And, of course, the winged inhabitants of Eheu Isle.