A burl (British "burr") is a rounded outgrowth on a tree trunk or branch that is filled with small knots from dormant buds. Burls yield a very peculiar and highly figured wood. There are a number of famous burls (each from a particular species); these are highly valued and used as veneers in furniture, picture frames, household objects, automobile interior paneling and trim, and woodturning.

Ingrid uses these unique woods in her boxes and clocks.