Strange quark
The first strange particle (a particle containing a strange quark) was discovered in 1947 (kaons), but the existence of the strange quark itself (and that of the up and down quarks) was only postulated in 1964 by Murray Gell-Mann and George Zweig to explain the Eightfold Way classification scheme of hadrons. The first evidence for the existence of quarks came in 1968, in deep inelastic scattering experiments at the Stanford Linear Accelerator Center. These experiments confirmed the existence of up and down quarks, and by extension, strange quarks, as they were required to explain the Eightfold Way.
Quack-monument
The Quack monument was originally founded in 1926 from a legacy of Arnoldus Burchard Adolphus Quack (Nijmegen, 6 April 1842 - Nijmegen, 11 November 1920). Quack was alderman of the municipality of Nijmegen from 1902 to 1919. The monument is named after him and his twin sister Maria (Marie) Christina (Nijmegen, April 6, 1842 - Nijmegen, March 15, 1905). Quack left his legacy to the municipality of Nijmegen under the condition that a fountain, the Marie Adolphron named after his sister, would be erected.