Also known as lace fat or crépine. In Spanish, it's also called redaño.

http://garbancita.blogspot.ca/2014/03/que-son-y-como-se-prep...
Se envuelve en redaño (crepineta o, como le denominan aquí, mantellina), que es una telilla grasa que sujeta los intestinos en la cavidad abdominal (es lo que si se rompe, provoca una hernia inguinal). Se cocina a la plancha y el toque a clavo, le da una personalidad única.

http://clinicasilvia.com/2017/01/31/figatell-que-es-y-como-c...
"El redaño o mantellina es una membrana veteada de grasa que se encarga de sostener los intestinos y el estómago del animal en la cavidad abdominal. Esta membrana se utiliza para envolver embutidos tales como el figatell o las longanizas, dándole forma a la carne."

https://www.thespruce.com/what-is-caul-fat-995601
"The third type of pork lard is caul fat. Caul fat is a lacy membrane of fat that surround the stomach and other digestive organs. It's sometimes called fat netting, and in France it is often referred to as crépine."

http://www.chefs-resources.com/types-of-meat/offal-varieties...
"From an anatomy perspective, caul fat is a web-like membrane which surrounds the intestines of animals including pigs, veal, beef, and lamb."