When stem cells grown on hard, rigid surface, then they became bone cells. Researchers demonstrate in Nature materials that human mesenchymal stem cells grown on a rigid substrate for some time become biased toward differentiating into bone-cell lineage, whereas cell grown on softer surfaces are just likely to eventually follow a bone or fat cell fate.
Because protists have traits that are similar to animals, plants, and fungi. Some protists have a mixture of all three. The three types of protists are Slime Molds, Algae, and Protozoans.
I hope this helped ^_^
~Renee