**Appendix A**

**Table A1.** Initial and final seed weights, including the duration of the experiment and the standardized weight change. Experimental identification corresponds to the aqueous conditions detailed in Table 1. The seed weight values are listed in grams, the experimental identification code is listed as Exp., the individual CaCO3 bioclast identification is listed under Seed, the initial weight and end weight of the seed material correspond to column *t0* and *te*, the number of days in the experimental conditions is in column D (variation in experimental duration was due to unexpected health and safety issues), and the standardized weight change per day (g d<sup>−</sup>1) is in column DΔ.


**Table A2.** The quantity of compounds (mg/5 L) added to the stock solution to obtain the experimental parameters outlined in Table 1.


**Figure A1.** CaCO3 polymorphs (aragonite, calcite, and vaterite) were identified via Raman spectroscopy, which were first morphologically identified by SEM on the incubated crystals. These Raman spectra were used to qualitatively identify the crystal structures found on the seeding crystals after incubation.
