1. Medical testing relies on horseshoe crab blood
"They are a (relatively) recent part of the production pipeline. Before introducing horseshoe crab blood, they used to inject rabbits and wait a couple of weeks." – beagle3
2. Concerns about the cruelty of harvesting
"Few things look more cruel and dystopic than the rooms where they harvest the blood of horseshoe crabs" – y-curious
3. Growing adoption of synthetic alternatives
"They have created a lab‑made alternative to test medicines, so no crabs are needed." – borski