I couldn't wait for the answer
In the 1960s, scientists discovered that the sky blue blood inside horseshoe crabs would clot when it detected bacterial toxins. Vaccines, drugs and medical devices have to be sterile before they're put inside people. A better toxin-detection system meant less contamination risk for patients
source (Trigger Warning: Begins with a photo of the blood collection many could find disturbing)
Didn't the same thing happen with authors and google 10+ years ago? That wasn't ever resolved, was it? Normally, I'd look it up, but I have a feeling I'd be spending time to be disappointed by the answer.