ultracold atomic gases can be observed through enhanced loss rates in three-body recombination and atom-dimer relaxation processes [@NM-99; @EGB-99; @BBH-00]. The first evidence for an Efimov trimer in a system of bosonic $^{133}$Cs atoms was presented by Kraemer [*et al.*]{}[@Kraemer:2006]. In a subsequent experiment with a mixture of $^{133}$Cs atoms and dimers, Knoop [*et al.*]{} observed a resonance in the loss of atoms and dimers [@Knoop:2008] which can be explained by an Efimov trimer crossing the atom-dimer threshold [@Helfrich:2009uy]. Efimov trimers have also been observed using other types of bosonic atoms. Zaccanti [*et al*]{}.[@Zaccanti:2008] found evidence for two adjacent Efimov trimers in a gas of ultracold $^{39}$K atoms and Gross [*et al.*]{} [@Gross:2009] measured two Efimov features across a Feshbach resonance and confirmed the universal relation between the features with $^7$Li atoms. Attached to each Efimov trimer are two universal tetramers which can be observed in four-body loss processes [@Platter:2004qn; @Hammer:2006ct; @Stecher:2008]. Ferlaino [*et al.*]{}[@Ferlaino:2009] observed signatures of two such tetramers close to an Efimov trimer with $^{133}$Cs atoms. In $^7$Li atoms, Pollack [*et al.*]{}[@Pollack:2009] have seen two sets of two tetramers that are close to the corresponding Efimov trimers.

Efimov physics can also occur in fermionic systems with three 