What actually happens inside genetic databases, how do they work upon data and who does this work? While they have become central tools for doing science, not much is known about the work that goes on inside these vital infrastructures. Ethnographic explorations of two of the world's largest nucleotide sequence databases, GenBank and the European Molecular Biology Laboratory's EMBL-Bank, reveal manifold goings-on. Like most infrastructural work, it is modest and invisible routines that build and maintain the vast interconnected suite of bioinformational resources. Data curators construct organisms out of sulphuric sludge, dataflow engineers as self-styled genetic information plumbers keep the data deluge flowing, and a data submissions support assistant manages to make room for care amidst this deluge. Taken together, these data labours render tangible the modest and processual aspects of data infrastructure while also revealing the databases to be situated and lively spaces of convergence. Inventively analysing data labours paves surprising ways for encountering and making sense of databases, data and the work they do. Here, practices of natural history, like specimen-making and curation, are continued by other means while the assembly of sludge sheds light on the absences and deletions which mystify infrastructural maintenance work.