Yet another rule question regarding pearls (Sorry)

[Googi]

Some bomy today seemed to pull a rule out of his ass about it being illegal for two bomys to use the same pearl level at the same time, now, the only rule I knew of is the one that doesn't allow you to take a pearl from a shell that a bomy was kicking. (Where can I find these rules anyways, as the Graal2001 page doesn't have any information on job-specific rules, only general ones).