36. Apart from coins, a range of other material groups from the repertoire of forms of the later La Tène culture (glass bracelets, swords, horse gear, bronze vessels, belt hooks, fibulae, etc.) occur rarely or not at all in the Belgian-Dutch coastal zone. On this subject, see Roymans 2007. The volume and the social impact of the production and exchange of sea salt by coastal communities remains a subject for debate. In the Iron Age, this salt probably circulated in a different sphere of exchange from that of coins.