In the mammalian skeleton, cartilage acts as a protective shock absorber. This connective tissue owes its elastic and buffering properties to the collagen-rich extracellular matrix that surrounds the chondrocytes (cartilage cells). But this is not all. Raul Ramos and Maksim Plikus (UC Irvine) and colleagues describe in the journal Science how so-called lipochondrocytes also play an important role in the biomechanical properties of cartilage in the ear, nose, larynx and other areas. These lipochondrocytes, first described in 1850, are actually fat-filled bubbles (linked to green fluorescent protein, GFP, in this image) that can be compared to bubble wrap in terms of their protective effect. Although the bubbles resemble normal adipocytes or fat cells, their formation and metabolism are very different. The lipochondrocytes appear to be disconnected from normal metabolism. In both obese and starved mice, these fat bubbles remained remarkably stable and kept their shape.