## 3 Experimental Results
### Microstructure and Micro-Area Composition of the Attached Marine Organism Remains
#### 3.3.2 Modular Organisms: Bryozoans and Red Coral  
As illustrated in Figure 6a, the skeletons of the Bryozoans attached to the outer wall of the sample were predominantly white, indicating that they were uncontaminated. The morphology of the Bryozoans suggested they belonged to the Schizophrenia family (see Figure 6b,c). Each zooecium was approximately 400 \(\upmu\)m in length and 150 \(\upmu\)m in width, featuring a slim-lined structure. Numerous spines were observed on the top wall of the zooecium. An orifice at one end of the zooecium likely served as an entry point for living Bryozoans (Figure 6b). The cross-sectional view revealed that the zooecium was roughly circular, with a diameter of 75 \(\upmu\)m (Figure 6c). Many zooecia were stacked to form a three-dimensional skeleton. The cross-section showed that both the bottom and interior walls of the Bryozoan were 25 \(\upmu\)m thick. An interspace was visible at the bonding interface between the bottom wall and the sample surface. The Bryozoans attached to the inner wall appear to be yellow white (Figure 6d), likely due to foreign pollutants deposited on the inner wall of the sample. Figure 6e shows that the aperture of the Bryozoan zooecium is 70 \(\upmu\)m in diameter; a calcareous ring structure can be observed on the fringe (referred to as Gymnolaemata in biology). Figure 6f reveals the presence of period spines on the peristome. The maximum diameter of the zooecium is up to 300 \(\upmu\)m, with the bottom wall thickness approximately 15 \(\upmu\)m and the thickness of the interior wall similar to that of the frontal wall (about 50 \(\upmu\)m). The Bryozoans are more tightly bound to the unglazed surface on the inner wall compared to the outer wall. However, noticeable interspaces remain at the bonding surface (Figure 6f). Three structural layers were observed from the top to the bottom wall: the cuticle, the mineralized layer, and the epithelia lining the body cavity. The cuticle was the outermost layer, interfacing between the Bryozoans and the external environment. The epithelia were the innermost layer, in contact with the polypides. The epithelia were distributed on both sides of the interior wall, lacking a cuticle. During the attachment process, undifferentiated epithelial cells on the bottom wall first secreted a cuticle; the adhesive for attachment was a simple acid mucopolysaccharideaccharide secretion that did not etch the sample surface [27] As epithelial cells differentiated, ionized calcium accumulated within the cells and was gradually released outside. Calcium salts were then deposited in the framework of the cuticle to form mineralized skeletons. Throughout this process, the outermost cuticle became at least partially mineralized, aiding in the fusion between the Bryozoans and the sample surface [28]. EDS analysis confirmed that both Bryozoans and other organisms had calcareous skeletons composed of aragonite calcium carbonate, with low magnesium content (see positions P4 and P5 in Table 3). The red coral was not firmly attached to the surface of sample DL. During the experimental process, some red coral skeletons entirely detached. Figure 7a shows that no residual glaze layer is present on the outer wall of sample DL-2. However, scanning electron microscopy (SEM) revealed that the surface of the outer wall beneath the red coral skeletons was densely pitted. This condition might be related to the shedding of anorthite crystal clusters from the interlayer between the glaze and the body. Unlike the bottom wall of the solitary coral, where the pits were completely filled by the coral skeletons, the red coral skeletons retained their original structure, with noticeable interspaces between the skeletons and the sample surface. The mode of attachment of red coral to the stoneware surface might be associated with the bio-mineralization process of red coral.