Though incredibly difficult, it is possible to extract the mutagenic mucus from the corpse of an aboleth and alchemically preserve it. This transparent slime is incredibly dangerous, 

A creature exposed to this substance must succeed on a DC 14 Constitution saving throw or become diseased. The disease has no effect for 1 minute and can be removed by any magic that cures disease. After 1 minute, the diseased creature's skin becomes translucent and slimy, the creature can't regain hit points unless it is underwater, and the disease can be removed only by heal or another disease-curing spell of 6th level or higher. When the creature is outside a body of water, it takes 6 (1d12) acid damage every 10 minutes unless moisture is applied to the skin before 10 minutes have passed. This transformation persists until the disease is cured; if the creature survives exposure to it for several years without being cured, they will continue to mutate until they are no longer recognizable.

Contact. Contact poison can be smeared on an object and remains potent until it is touched or washed off. A creature that touches contact poison with exposed skin suffers its effects.