A spectroscopic method and system to identify a biofilm of a microorganism. A sample containing a sample microorganism is irradiated with substantially monochromatic radiation. A Raman data set is obtained based on radiation scattered from the irradiated sample. A database is searched in accordance with the Raman data set in order to identify a known Raman data set from the database. The database contains a plurality of known Raman data sets where each known Raman data set is associated with a known sessile form of a corresponding known microorganism. A sessile form of the sample microorganism is identified based on the known Raman data set identified by the searching.