 The methodology and epistemology of modelling with model organisms is a topic of increasing discussion in the history and philosophy of science (Ankeny &amp; Leonelli 2011; Endersby 2007; see also the  SEP entry on experiment in biology).  These discussions include recent debates about what sorts of models model organisms are, and whether they qualify as genuine models. A number of philosophers of modelling classify model organisms in the same category as other physical analogue models, such as the model airplanes used in studies of aerodynamics or the sandboxes used to model geological processes in laboratories (Weisberg 2013; McClay and Dooley 1995;  SEP entry on models in science).  However, Levy &amp; Currie (2015) object to this practice, arguing that model organisms are not theoretical models in the sense of interpreted structures studied as analogues of target systems in the natural world. Instead, they see organismal models as specimens of (and thereby bases for extrapolation about) broader classes of organisms. Levy and Currie do, however, concede that in some contexts, such as experimental evolution and ecology, organismal models can play a very similar role to that of theoretical models. Microbes are common choices for this role as analogue systems in experimental settings.