The most useful habit a reader can bring to this subject is asking, of any statement about a sign, where it came from.
Good sources answer that question without being asked. They name the diviner, the house, the town and the date, they distinguish what they observed from what they were told, and they say where they were refused. Bascom in 1980 and Cabrera in 1954 both do this to differing degrees, which is why they remain the load-bearing references despite their age. Poor sources answer it not at all, and the great bulk of what circulates on the sixteen signs is of that kind.
Provenance is also the reason the atlas can say some things confidently and others not at all. That Marunla is the fifteen-mouth throw follows from the mechanics of the cast and is not in dispute anywhere. That it means any particular thing is a claim whose provenance, on inspection, usually evaporates.
Marunla is one of the four upper signs named by shell count and among the rarest in ordinary practice. Its interpretive content is conferred within initiated Lucumi lineages and is not reproduced here.
Age is the honest weakness of both. A book from 1954 or 1980 describes practice as it stood then, and Lucumi practice has continued to develop in Cuba, in Miami and in West Africa since. A well provenanced old source remains better evidence than an unprovenanced new one, but it is evidence about a date, and the atlas records it that way.