Conus purpurascens, also commonly called as the "Purple shell" or the "South sea cone shell" is a mollusk which can be found in the central pacific islands. The mollusk is primarily known for its deadly neurotoxin, which was used in the Lindstradt Air Gun, owned by Eddie Carr.

"It's the most powerful neurotoxin the world. Acts within a 2000th of a second making it faster than the nerve conduction velocity. So the animal is down before it feels the prick of the dart." 
Arriving to Isla Sorna02:12

Arriving to Isla Sorna

The Conus Purpurascens is first mentioned in this scene.