Anchoring is the problem of how to connect, inside an artificial system, the symbol-level and signal-level representations of the same physical object. In most previous work on anchoring, symbol-level representations were meant to denote one specific object, like 'the red pen p22'. These are also called definite descriptions. In this paper, we study anchoring in the case of indefinite descriptions, like `a red pen x'. A key point of our study is that anchoring with an indefinite description involves, in general, the selection of one object among several perceived objects that satisfy that description. We analyze several strategies to perform object selection, and compare them with the problem of action selection in autonomous embedded agents.