The alien razor shell Ensis americanus (Binney) is a common bioclast on Dutch beaches. It is uncommonly encrusted by the balanid Balanus crenatus Brugière on both the interior and exterior surfaces of both valves. This occurs postmortem, but before the ligament breaks. A well-preserved specimen from Zandvoort is described which confirms that this pattern of skeletozoan infestation is initiated in dead shells still in the burrow, but protruding above the sediment surface. After exhumation, the recumbent shell can be further infested by subsequent balanid spatfalls. Such a pattern of encrustation is only likely in burrowing bivalves with a permanent and prominent gape to the shell.

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