 Levels of mechanisms share some key features with the more standard accounts of levels of organization: They are by definition compositional, entities at higher levels are typically larger than entities at lower levels, and levels of mechanisms can potentially amount to local peaks of regularity and predictability (Craver 2007: 190; see next section). However, levels of mechanisms are far more limited and minimalistic than any other extant approaches to levels of organization. First of all, as already mentioned, levels of mechanisms can only be identified on a case-by-case basis, and different mechanisms can have entirely different levels. For example, the set of levels in the mechanism of protein folding is very different from the levels in the spatial memory mechanism.