library_construction_protocol: planarians were chopped and dissociated in CMFB (CMF+1% FBS) on a cold plate (4 °C). Cells were strained through a 40um strainer and stained with DAPI (1:1000; Beyotime) and DRAQ5 (1:1000; BioStatus). Flow cytometry and sorting were conducted on a Sony MA900 cell sorter. Around 20,000 cells were loaded into SeekOne' Microwell & Magnetic Beads platform for making single-cell libraries.