Crab serum

A man goes to the doctor and is diagnosed with an unusual condition.

The doctor tells him there is a new drug made from crab serum that he might like to try.

The patient agrees and is told to visit the doctor again in a weeks time as the crab serum is experimental.

After two days, the man finds he is unable to step forwards or backwards and is only able to shuffle from left to right or right to left.

He shuffles into the doctors one week later and his GP asks about his condition.

The man replies that he feels much better, but he now cannot step forwards or backwards but can only shuffle from left to right or right to left.

The doctor replies "Well I did warn you that this crab serum may have side effects."

Horseshoe crabs are harvested, blood drawn, and returned to the ocean.

Horseshoe-crab blood is exquisitely sensitive to toxins from bacteria. It is used to test for contamination during the manufacture of anything that might go inside the human body: every shot, every IV drip, and every implanted medical device.