The first space hamsters were created by wizards who used magic to shrink giant space hamsters to wee size, leading their creators to refer to them as miniature giant space hamsters. The magic also made the space hamsters smarter and telepathic.
-These benign rodents are native to Wildspace, though countless numbers of them have found their way to worlds throughout the Material Plane, where they are known simply as hamsters. They keep their telepathic ability hidden from most other creatures they come near.
+A jammer leech is a barnacle-like creature that begins life as a space-dwelling spore that attaches to the hull of a spelljamming ship, with the leech inside in larval form. A spore that remains attached to a ship for a few days punctures the hull and begins to develop a hard shell that roughly matches the color of the hull. The shell is affixed to the ship by a glue-like substance secreted by the leech. The shell grows until it's about 1 foot in diameter. The leech inside is reddish-purple in color, with a body resembling that of a snail. It has a single watery eye at one end and a spiked tentacle protruding from just below the eye, which it uses to defend itself.
+A mated pair of leeches produces 1d6 spores every month. Some of these spores might join their parents on the hull of the ship, while others float off, waiting to attach themselves to another unwary vessel.
+A jammer leech damages the hull of the ship to which it is attached and absorbs magic from the ship's spelljamming helm. It can discharge this magic from time to time as a defensive measure. If the crew of a ship becomes aware of leeches that have become attached, it's customary for them to try to scrape the leeches off the hull rather than attack them with weapons. Killing a leech while it is attached to the ship is dangerous, because the trauma of its death can be felt by the ship's spelljammer, who is weakened and incapacitated by the shock.
When it takes damage, the leech can discharge a bolt of magical energy from its eye that targets one creature it can see within 30 feet of itself. The target must succeed on a DC 13 Dexterity saving throw or take 10 (3d6) force damage and be stunned until the end of its next turn.