Transverse Single-Spin asymmetries (TSSAs) of proton-proton collisions have a long history of revealing the richness of QCD. Large TSSA were originally discovered in fixed target experiments but have been found to persist in collisions up to \(\sqrt{s} = \) 510 GeV and transverse momenta up to about 7 GeV, well into the perturbative regime of QCD, and yet their origin remains poorly understood. TSSA measurements have allowed for the development of both transverse momentum dependent and collinear twist-3 descriptions of nonperturbative spin-momentum correlations in the nucleon as well as in the process of hadronization. As hadrons, eta mesons are sensitive to both initial- and final-state nonperturbative effects for a mix of parton flavors. Their comparison to neutral pions may provide information on potential effects due to strangeness, isospin, or mass. The status of the TSSA of eta mesons at midrapidity for 200 GeV proton-proton collisions from the PHENIX 2015 data set will be shown.