Figure 2: Aggregates of NPs in sea water after 48 h and into sea urchin larvae exposed to contaminated microalgae (ESEM image). Images show SiO2, SnO2, CeO2, Fe3O4 NP aggregates and size in sea water (a-d) e in sea urchin larvae (e) exposed to Fe3O4 NPs. Bar 9 μm.