## 3 Experimental Results  
### Morphology of the Attached Marine Organism Remains  
The influence of bio-attachment on the appearance of Shard DL was evident, with more than 90% of the surface area covered with stacked marine organism remains. Notably, more organisms were attached to the unglazed inner wall than to the glazed outer wall. Optical microscope (OM) images were taken of marine organism remains with different morphologies. The attached organisms were classified into the following two types: (1) unitary organisms including Serpulids and solitary coral (i.e., self-maintaining units derived from a single zygote [14]); and (2) modular organisms including red coral and Bryozoans (i.e., structural individuals consisting of more than one iterated basic unit [15]). These marine organisms were not only directly attached to the surface of the stoneware but were also found atop marine plant coralline algae, forming biological stacking and attachment.  
The solitary coral attached to the outer wall of sample DL-4 was a type of polypoid coral belonging to the class Anthozoa of the phylum Coelenterata. The top diameter of the epitheleca, showing white cylinders, was approximately 3 mm, and the covering diameter of the bottom wall was up to 8-10 mm. The septum, with an overall radial symmetry, resembled wheels (Figure 2a). There were gaps of more than 100 microns between the walls, with numerous jagged protuberances on the surface. Some epithea were intact, with a vertical height of 3-5 mm. Some corals were in the early growth stage, with almost no cylindrical epitheca observed. During the lifetime of Anthozoans, the septum supported the polypoid on the top floor of the skeleton, with sunken soft tissues existing in the interspace between septa.  
Numerous Serpulid tubes were observed on the surface of sample DL-2. Serpulids are a type of annelid belonging to the class Polychaeta of the phylum Annelida, characterized by yellow-white hollow tubes. The tubes varied in length (10-20 mm) and thickness (approximately 0.5 mm). As shown in Figure 2b, two parallel ridges were observed on the tube top. Polypides originally lived inside the tubes, and it was not easy to peel off the calcareous tubes left after the death and degradation of the polypeptides from the surface [16; 17].  
Both the red coral and solitary coral belonged to the class Anthozoa of the phylum Coelenterata. Some striped or dotted red coral remains were found on both the inner and outer walls of sample DL-2, with varying lengths (from 2 to 20 mm) and shades of red. The surface was loose and porous. As shown in Figure 2c, the remains were dendritic group skeletons formed by biomineralization when a large number of red Anthozoans (polypoids)gathered. The red color of the skeleton was sourced from polyenes when the Anthozoan preyed on plankton [18].  
The Bryozoan attached to the inner wall of sample DL-5 belonged to the phylum Bryozoa. They were fixed in a benthic pattern and grew in a covering pattern [19]. Many yellow-white fan-shaped or flaky group skeletons were found to spread on the surface. As shown in Figure 2d, a single Bryozoan was approximately 0.5 mm in length. While the Bryozoans constantly bred new individuals in a sprouting pattern, the formed group skeletons reached a considerably large coverage area. Figure 2d showed individual zoecium structures with a clear boundary. The large circular hole, located on the top, was the orifice of the zoecium that served as the access channel for Bryozoans. The small circular hole was the pore, a fine structure of the Bryozoan skeleton.