Horseshoe Crabs

Horseshoe crabs are rare creatures that go to the shore every 10 years to spawn (give birth/ lay eggs).
When they do, scientists harvest (collect) some of their blood because it amazing properties.

Their blood contains cells called amebocytes, cells that form a gel around pathogens, to prevent them from spreading. It is injected into our bodies to contain certain viruses.

Unfortunately, 15% of horseshoe crabs die during blood harvest. And are sometimes unable to spawn because we interrupt them. They also go to spawn-sites less often because build on them.

Reference: TedEd