Enables sphingomyelin phosphodiesterase activity. Involved in cellular response to tumor necrosis factor; ceramide biosynthetic process; and sphingomyelin catabolic process. Acts upstream of or within in utero embryonic development. Located in endoplasmic reticulum; nuclear envelope; and sarcolemma. Is expressed in cranium; hemolymphoid system; nervous system; respiratory system; and urinary system. Orthologous to human SMPD4 (sphingomyelin phosphodiesterase 4). [provided by Alliance of Genome Resources, Apr 2022]