Blue Bloods

I routinely toss horseshoe crabs back into the Chesapeake when they appear to be struggling on the beach. I knew they had some kind of medical use but never knew what, until now (sort of).

From Horseshoecrab.org (or course)...

The horseshoe crab plays a vital, if little-known, role in the life of anyone who has received an injectable medication. An extract of the horseshoe crab's blood is used by the pharmaceutical and medical device industries to ensure that their products, e.g., intravenous drugs, vaccines, and medical devices, are free of bacterial contamination. No other test works as easily or reliably for this purpose.

An interesting side note, horseshoe crabs used to produce the extract are caught and then released after 30% of their blood is removed.