Plastic has rapidly become the characteristic material of the current Plastic Age, determining part of the archaeological record and a new category of cultural heritage. The presence of plastic waste material, stratified across ecosystems worldwide, can be conceptualized within the semiotic discourse as “toxic heritage”. This extends into the future, acknowledging that waste materials undergo a phase of plasticity, transitioning from elasticity to eventual fracture. The analysis aims to illustrate, firstly, how the evolving forms of plastics, originating as mundane everyday objects, transform into heritage artifacts, only to degrade into potentially hazardous micro- and nano-plastics, subsequently diminishing in significance as heritage and often becoming environmentally destructive. Furthermore, this study will examine the ecological impact of plastics, analyzing plastic waste from both semiotic and ecological perspectives. It will elucidate how plastic waste disrupts ecological memory, which denotes the influence of past states or experiences on present or future responses by ecological communities. The purpose is to show how plastic changes the debate on cultural and natural heritage, connecting them through the insights offered on current response strategies to the plastic problem. This will be demonstrated through various case studies showcasing strategies and methodologies for reinterpreting plastic waste and addressing the issue through action-oriented approaches such as recycling, upcycling, artistic interventions, toxic tours, museum activism, and citizen projects. These strategies establish the vital role that heritage initiatives must take in reshaping the future of waste materials within a framework of sustainability, exploring the historical and mnemonic significance of plastic.