Its a version of blood sausage made with rice. It's
(a) not importable to the US.
(b) not carried at Despana (because of (a))
(c) apparently impossible to find US-made versions. The manager at Despana had no idea where I could track one down. The only Spanish expat that I know was similarly baffled.
I see it available at tienda.com, but I'm leery of buying blood sausage mail-order. Do any restaurants/stores in the tristate area make this?