Before you can measure a cell, you have to draw its outline — and for a decade every new microscope, stain, or organism meant training a new bespoke segmenter. The ‘Segment Anything’ moment changed the terms: a single promptable foundation model, adapted to the messy reality of microscopy. Two 2025 works make it real for biology — Cellpose-SAM, a preprint claiming ‘superhuman generalization’ by grafting SAM’s backbone onto Cellpose, and Segment Anything for Microscopy (μSAM), a Nature Methods tool that does interactive and automatic segmentation across 2D, 3D, tracking, light and electron microscopy in one open napari plugin — and publishes its models straight into the BioImage Model Zoo. It’s the lab’s home turf, and the load-bearing first step under spatial omics and a virtual cell.