Rippers

In the final phase of a Tyranid invasion, billions of voracious Tyranid organisms are released over the planet. They move across its surface multiplying and and consuming everything, leaving an empty and desolate wasteland. Eventually they are reabsorbed by the hive fleet and their biomass is used to create more complex creatures. These organisms are extremely varied but the most common are known to Imperial forces as Rippers. These are energetic and persistent, so are quite capable of pulling down creatures many times their own size.