Clownfish taking a bite out of frogspawn?

[Mariaface]

Clownfish like to 'clean' their hosts, which can include biting off bits they feel are 'weak'. Keep your coral healthy and happy (keep feeding and dosing or keeping up with water changes to maintain water parameters), so it'll have the resources to put up with a clown trying to make a home in/on it. Clowns will also nibble at the coral/anemone to adjust to its sting, but that generally doesn't include biting pieces off completely.