Sea lemon?

Sea lemon?

Observation - Sea lemon?. Description: Observed between Bognor Regis and Littlehampton, on the beach in the driftline. Overall, it was about 8 cm long and 3 cm thick. Could anyone provide and ID? Thanks.

Observed between Bognor Regis and Littlehampton, on the beach in the driftline. Overall, it was about 8 cm long and 3 cm thick.
Could anyone provide and ID? Thanks.