Female guppies (Poecilia reticulata) sometimes bring a little extra baggage to a relationship—in the form of a dead male’s sperm.

A new study shows that one in four wild guppies in Trinidad and Tobago are fathered by the sperm of dead males. Some of these sperm have been stored for long enough that these males could otherwise be the grandfathers of these fish-to-be.

After mating, female guppies store sperm in a specialized cavity in their ovaries, keeping it alive with small amounts of sugar until the eggs are fertilized. (Also see “Why Female Flies Eat Sperm.”)

Why store sperm? Female guppies outlive males by at least a year, so storing sperm from multiple mating partners gives the female a choice