The Physalia is a form of sea life which drifts through tropical waters. It has a sail-like bulb at the top and a tangle of extendable tentacles underneath. It is poisonous and will give painful stings to any human who touches it. I envisioned spaceships built like Physalia, with a hard central shell and long streamers reaching outward from it. Perhaps the streamers are a form of biomorphic space drive, as there doesn't seem to be any conventional form of propulsion. Probably the aliens who travel in these ships resemble Physalias, and are used to either aquatic or zero-G life. The stings would be bursts of radiation which would burn anything that came into contact with the streamers.
"Physalia-ships" is acrylic on illustration board, 10" x 7", September 1990.