We performed single-cell transcriptome analysis (using 10x) of four placozoan species (Trichoplax adhaerens, Trichoplax sp. H2, Cladtertia collaboinventa, Hoilungia hongkongensis). Additionally we performed bulk ATAC-seq experiments and anti-H3K4me2/anti-H3K4me3 ChIP-seq experiments the same species. Overall design: Adult specimens were fixed, dissociated and pooled before sorting single-cells for scRNAseq. Some samples were mixed (cross-species or cross-treatments) and processed together. Instructions for demultiplexing cells are provided. Please note that the processed data for the scRNA-seq samples are generated from multiple samples (as indicated in the corresponding sample descriptionfield) and thus is linked to the Series records.