boring sponge

noun

: any sponge of Cliona or related genera that penetrates the substance of shells, some species (such as C. celata) of the Atlantic coast being injurious to oysters

Love words?

You must — there are over 200,000 words in our free online dictionary, but you are looking for one that’s only in the Merriam-Webster Unabridged Dictionary.

Start your free trial today and get unlimited access to America's largest dictionary, with:

• More than 250,000 words that aren't in our free dictionary
• Expanded definitions, etymologies, and usage notes
• Advanced search features
• Ad free!