This study is a sequel to a previous study entitled Thinging for Software Engineers, which showed that the notion of thing, in contrast to objectification, has some beneficial orientations in modeling. The incorporation of thinging in conceptual modeling is required to explain the roots of Heidegger s conception of things. This requires an understanding of Heidegger s existential ontology to identify any relationship to thinging. This paper is an exploration of existential ontology in search of further clarification of the concept of thinging. We start by reviewing the thinging machine (TM) introduced in Thinging for Software Engineers and provide a full example of its utilization in modeling an ordering system. We follow this with a discussion of the being (existence) of things in the word and Heidegger s interpretation of time as a possible horizon for any understanding whatsoever of being. We emphasize that the TM is not related directly to the Heideggerian notion of existence and its elaborate analysis of Dasein. However, there may be some benefit to studying non-Dasein things to provide a philosophical foundation to thinging, as utilized in TM modeling. Interestingly, the TM can be utilized to model existential ontology, thus increasing the level of understanding about them.