East Lindsey District Council has confirmed that the substance founds on beaches in Mablethorpe and Skegness in recent weeks has now been identified as petroleum wax.
The substance was previously believed to be palm oil.
An ELDC spokesman said: “We’ve been dealing with numerous incidents where a substance has washed up on our beaches.
“We’ve now had the results from the testing on substance, which has been identified as Petroleum Wax.
“Our advice remains the same: do not remove or touch the substance and please report it.”
Members of the public are advised not to touch or remove the substance, and instead report it to ELDC on 01507 601111.
Anyone who accidentally comes into contact with the substance is advised to wash it off with soap or shower gel, and wash their clothes.
Dog-walkers are urged to keep their pets away from the substance, and to contact their vet as soon as possible if their dog shows signs of ill-health after being in contact with it.