Extracellular matrix protein that may serve as substrate for the migratory primary mesenchyme cells (PMCs), the interaction possibly providing guidance information to migrating PMCs. Component of extracellular matrix fibers that interact with PMC filopodia during gastrulation (at protein level). The Calx-beta domains bind calcium with high affinity and undergo a major conformational shift upon binding. Belongs to the FRAS1 family.