This paper explores the intersection of environmental education, collaborative artistic practices, and heritage through the case study Trash + Fantastic Beasts. Developed by faculty and students from the Universities of Zaragoza and Porto, the project engages participants in creating sculptural artworks using recycled materials inspired by the medieval bestiary of the Mudejar ceiling in Teruel Cathedral. Drawing on Trash Art as a pedagogical and aesthetic approach, the initiative aims to foster environmental awareness and critical reflection on consumerism, waste, and sustainability. By integrating artistic creation with community involvement and heritage interpretation, the project redefines waste as a meaningful cultural and educational resource. The methodology emphasizes co-creation, active participation, and interdisciplinary collaboration, encouraging students to explore alternative narratives of memory, identity, and ecological responsibility. Through exhibitions, educational workshops, and international exchanges, Trash + Fantastic Beasts serves as a model for how contemporary art practices can contribute to sustainability education and the development of eco-social aesthetics. This case highlights the potential of art education to inspire agency and dialogue across generations, institutions, and cultural contexts.