  A recent analysis by the LHCb collaboration suggests the existence of three
narrow pentaquark-like states --- the $P_c(4312)$,$P_c(4440)$ and $P_c(4457)$
--- instead of just one in the previous analysis (the $P_c(4450)$). The
closeness of the $P_c(4312)$ to the $\bar{D} \Sigma_c$ threshold and the
$P_c(4440)$/$P_c(4457)$ to the $\bar{D}^* \Sigma_c$ one suggests a molecular
interpretation of these resonances. We show that these three pentaquark-like
resonances can be naturally accommodated in a contact-range effective field
theory description that incorporates heavy-quark spin symmetry. This
description leads to the prediction of all the seven possible S-wave heavy
antimeson-baryon molecules (that is, there should be four additional molecular
pentaquarks in addition to the $P_c(4312)$, $P_c(4440)$ and $P_c(4457)$),
providing the first example of a heavy-quark spin symmetry molecular multiplet
that is complete. If this is confirmed, it will not only give us an impressive
example of the application of heavy-quark symmetries and effective field
theories in hadron physics: it will also uncover a clear and powerful ordering
principle for the molecular spectrum, reminiscent of the SU(3)-flavor
multiplets to which the light hadron spectrum conforms.
