In this paper, I will discuss the need for a theory of essences within Object-Oriented Ontology (OOO) and then formulate one. I will do so by drawing on Graham Harman’s work on OOO and Martin Heidegger’s thought on the essence of being, presented in his Introduction to Metaphysics. Harman touches on essences, describing them as the tension between a withdrawn object and its withdrawn qualities, but fails to distinguish between essential and inessential qualities within this framework. To fill in the gaps, I will turn to Heidegger’s explication of phusis in order to show that an essential aspect of being is how one enters into causal relations and continually reveals oneself to other beings. In bringing OOO and Heidegger together, I will find that each object has a unique way of exerting itself in the world and that the domestic relations that make up this unique profile are essential to it, while other domestic relations, those that do not influence its particular way of exerting itself, are inessential. Thus, the essence will be found to be the set of domestic relations that make up the determinate form, or unique causal profile, of the object.