The siphons at either end of the Makassar Salp (Pegea pacifica) can dilate sufficiently to allow other animals to crawl or swim inside the body (1). Typically such an intruder is ejected during propulsion, but occasionally may become lodged. In these circumstances, the salp’s usual recourse is to expel all water and contract at both ends, suffocating the creature in a vacuum (2). The salp may itself die in the process, and then harden — resulting in an attractive, semi-opaque object shaped like a bird’s egg (3). “Mermaid grenades,” as these floating trinkets are often called, are commonly gleaned by Coelobonese fishermen and sold as souvenirs.