Aim and objectives: To critically discuss the ontological framework of Fundamentals of Care (FoC), as developed by Uhrenfeldt, et al. (2018), Journal of Clinical Nursing, 27, 3197–3204; to suggest theoretical improvements by taking a wonder-based approach; and to show how this approach can be applied in healthcare sectors. Background: Based on a critical discussion of a discursive study on the ontology of FoC, studies in phenomenology of wonder and two action research projects involving “Wonder Labs,” this article discusses whether the ontology and reflective practices behind FoC can be qualified further by an existential phenomenology of wonder and with practices of “Wonder Labs.”. Design: This is a discursive study critically discussing Uhrenfeldt et al.'s primary focus on dyadic and relational openness and person-oriented attentiveness in a nurse–patient relationship. This is done by unfolding the phenomenology of wonder and wonder experiences at a hospice and a hospital, and by critically examining the psychologically influenced interpretation of Heidegger. Conclusion: The first attempts by Uhrenfeldt et al. to identify the philosophical roots and ontology of FoC by pointing to existential phenomenology and philosophy are acknowledged. However, in this article, we further elaborate this attempt by focusing on the phenomenology of wonder. We show that Heidegger speaking about “existential homecoming” referred to a philosophical practice focusing on the resonance with being, rather than on interpersonal and psychological relations. In conclusion, the article recognises the importance of integrating these two approaches described on the one hand as a person-oriented and lifeworld-led approach, and on the other hand as a being- and phenomenon-oriented approach to the nurse–patient relationship. Relevance to clinical practice: To be open to the “musicality” of the being dimension, as the core values of FoC, a wonder-based approach to value clarifications and phenomenological dialogues is pivotal for the presence of openness, trust and attentiveness of the nurse–patient relationship. The practices of the “Wonder Lab” may be an approach for training nurses in hearing the call of this “ontological resonance.”.