Biomaterials start-up altM has raised a $3.5 million seed round led by Omnivore. The round saw participation of investors including Theia Ventures, Thai Wah Ventures, Sanjiv Rangrass, Neha Mudaliar, Maninder Gulati from OYO, Mirik Gogri from Spectrum Impact, and Paula Mariwala from Aureolis Ventures.