This enemy is found only in the old-gen console and Nintendo 3DS version(s) of Terraria.
For the weaker variant, see Gastropod
The Spectral Gastropod, is an old-gen console- and Nintendo 3DS-version variation of the Gastropod monster. It is found in the Hallow after Hardmode has been enabled. Similar to the Gastropod, shooting the Spectral Gastropod while it is preparing its laser will cause it to retreat back into its shell and not shoot the charging shot.
Because they are just a stronger variant of the Gastropod, any strategy used for their weaker variants applies to them. Caution is advised when fighting them, however, especially with weaker armor and weapons.