It looks soft. Is it squishy, brittle, or otherwise infirm? Can you pick chunks out with your fingernail? If it's squishy, don't put it in your tank. It'll just jack your organics way up as it breaks down and you'll be fighting algae in no time. If it's solid, then as mentioned above, boil and scrub several times before introducing. A bleach dip may be good as well.