We have found that our alginate moulds have started to grow themselves! This was so interesting and a great surprise for us. We found that the casts with food colouring in them have grown considerably more than those without, which is interesting. They have also shrunk considerably as the water content has decreased.
When attempting to research why this happens and what causes the mould to happen, there was no information that I could find. I assume that there is a certain level of nutrients within the seaweed used to make alginate and that when left in a warm and damp environment, mould forms, as it would on bread. Since these photos, we have put them into containers to see how far they would shrink down, so far they have shrunk to over half of their original size!