Ediacaran rangeomorphs were the first substantially macroscopic organisms to appear in the fossil record, but their underlying biology remains problematic. Although demonstrably heterotrophic, their current interpretation as osmotrophic consumers of dissolved organic carbon (DOC) is incompatible with the inertial (high Re) and advective (high Pe) fluid dynamics accompanying macroscopic length scales. The key to resolving rangeomorph feeding and physiology lies in their underlying construction. Taphonomic analysis of three-dimensionally preserved Charnia from the White Sea identifies the presence of large, originally water-filled compartments that served both as a hydrostatic exoskeleton and semi-isolated digestion chambers capable of processing recalcitrant substrates, most likely in conjunction with a resident microbiome. At the same time, the hydrodynamically exposed outer surface of macroscopic rangeomorphs would have dramatically enhanced both gas exchange and food delivery. A bag-like epithelium filled with transiently circulated seawater offers an exceptionally efficient means of constructing a simple, DOC-consuming, multicellular heterotroph. Such a body plan is broadly comparable to that of anthozoan cnidarians, minus such derived features as muscle, tentacles and a centralized mouth. Along with other early bag-like fossils, rangeomorphs can be reliably identified as total-group eumetazoans, potentially colonial stem-group cnidarians.

Ediacaran rangeomorphs 是第一个出现在化石记录中的宏观生物，但它们的潜在生物学仍然存在问题。虽然可以证明是异养的，但它们目前作为溶解有机碳 (DOC) 的渗透性消耗者的解释与伴随宏观长度尺度的惯性（高Re）和平流（高Pe ）流体动力学不相容。解决范围形态摄食和生理问题的关键在于它们的潜在结构。三维保存的查尼亚的埋藏分析来自白海的研究确定了最初充满水的大型隔间的存在，这些隔间既可用作静水外骨骼，也可用作能够处理顽固底物的半隔离消化室，最有可能与常驻微生物组结合使用。同时，宏观范围形态的流体动力学暴露外表面将显着增强气体交换和食物输送。充满瞬时循环海水的袋状上皮提供了一种非常有效的方法来构建简单的、消耗 DOC 的多细胞异养生物。这样的身体结构与珊瑚虫刺胞动物的身体结构大致相当，减去了肌肉、触手和集中嘴等衍生特征。与其他早期的袋状化石一起，