An algae-based thermoplastic foam is provided having a protein-rich algae biomass selected from either microalgae, macroalgae or combinations thereof. The protein content is greater than or equal to 15% by weight of the algae biomass and the algae biomass is dried to a moister content of less than or equal to 15% by weight having an average particle size of up to 200 microns. The composition includes a resin configured to exhibit rheological properties suitable for blending with algae including a melting temperature less than 250° C. and a melt flow rate in excess of 0.01 g/10 min. The foam includes a foaming ingredient selected from the group consisting of crosslinkers, compatibilizers, plasticizers, accelerants, catalysts, blowing agents, other ingredients, and combinations thereof.