Cattle mesentery 
Bovine mesentery: the fold of peritoneum that holds the intestines, obtained from the slaughterhouse.
Characteristics
- It is a thin membrane, rich in fat and blood vessels.
- In biodynamics it is the casing of preparation 506 (dandelion).
- It is used fresh or salted, wrapping the flowers into parcels.
Role in the preparation: The wrapped flower parcels are buried in autumn and dug up in spring.
Caution: In the EU bovine mesentery is specified risk material (Regulation (EC) 999/2001): check before sourcing it and follow animal-health rules.
Sources: Biodynamic agriculture - Wikipedia · Mesentery - Wikipedia · Regulation (EC) 999/2001 - EUR-Lex
Documentary information: this is neither a recommendation for use nor a plant-protection or veterinary claim. Check your country's regulations before any use.